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RFC 2566 - Internet Printing Protocol/1.0: Model and Semantics


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Network Working Group                                           R. deBry
Request for Comments: 2566                     Utah Valley State College
Category: Experimental                                       T. Hastings
                                                       Xerox Corporation
                                                              R. Herriot
                                                       Xerox Corporation
                                                             S. Isaacson
                                                            Novell, Inc.
                                                               P. Powell
                                                     Astart Technologies
                                                              April 1999

          Internet Printing Protocol/1.0: Model and Semantics

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

IESG Note

   This document defines an Experimental protocol for the Internet
   community.  The IESG expects that a revised version of this protocol
   will be published as Proposed Standard protocol.  The Proposed
   Standard, when published, is expected to change from the protocol
   defined in this memo.  In particular, it is expected that the
   standards-track version of the protocol will incorporate strong
   authentication and privacy features, and that an "ipp:" URL type will
   be defined which supports those security measures.  Other changes to
   the protocol are also possible.  Implementors are warned that future
   versions of this protocol may not interoperate with the version of
   IPP defined in this document, or if they do interoperate, that some
   protocol features may not be available.

   The IESG encourages experimentation with this protocol, especially in
   combination with Transport Layer Security (TLS) [RFC 2246], to help
   determine how TLS may effectively be used as a security layer for
   IPP.

Abstract

   This document is one of a set of documents, which together describe
   all aspects of a new Internet Printing Protocol (IPP).  IPP is an
   application level protocol that can be used for distributed printing
   using Internet tools and technologies.  This document describes a
   simplified model consisting of abstract objects, their attributes,
   and their operations that is independent of encoding and transport.
   The model consists of a Printer and a Job object.  A Job optionally
   supports multiple documents.  IPP 1.0 semantics allow end-users and
   operators to query printer capabilities, submit print jobs, inquire
   about the status of print jobs and printers, and cancel print jobs.
   This document also addresses security, internationalization, and
   directory issues.

   The full set of IPP documents includes:

     Design Goals for an Internet Printing Protocol [RFC2567]
     Rationale for the Structure and Model and Protocol for the Internet
        Printing Protocol [RFC2568]
     Internet Printing Protocol/1.0: Model and Semantics (this document)
     Internet Printing Protocol/1.0: Encoding and Transport [RFC2565]
     Internet Printing Protocol/1.0: Implementer's Guide [ipp-iig]
     Mapping between LPD and IPP Protocols [RFC2569]

   The "Design Goals for an Internet Printing Protocol" document takes a
   broad look at distributed printing functionality, and it enumerates
   real-life scenarios that help to clarify the features that need to be
   included in a printing protocol for the Internet.  It identifies
   requirements for three types of users: end users, operators, and
   administrators.  It calls out a subset of end user requirements that
   are satisfied in IPP/1.0.  Operator and administrator requirements
   are out of scope for version 1.0.

   The "Rationale for the Structure and Model and Protocol for the
   Internet Printing Protocol" document describes IPP from a high level
   view, defines a roadmap for the various documents that form the suite
   of IPP specifications, and gives background and rationale for the
   IETF working group's major decisions.

   The "Internet Printing Protocol/1.0: Encoding and Transport" document
   is a formal mapping of the abstract operations and attributes defined
   in the model document onto HTTP/1.1.  It defines the encoding rules
   for a new Internet media type called "application/ipp".

   The "Internet Printing Protocol/1.0: Implementer's Guide" document
   gives insight and advice to implementers of IPP clients and IPP
   objects.  It is intended to help them understand IPP/1.0 and some of

   the considerations that may assist them in the design of their client
   and/or IPP object implementations.  For example, a typical order of
   processing requests is given, including error checking.  Motivation
   for some of the specification decisions is also included.

   The "Mapping between LPD and IPP Protocols" document gives some
   advice to implementers of gateways between IPP and LPD (Line Printer
   Daemon) implementations.

Table of Contents

1. Introduction                                                        8
 1.1   Simplified Printing Model                                       9
2. IPP Objects                                                        11
 2.1   Printer Object                                                 12
 2.2   Job Object                                                     14
 2.3   Object Relationships                                           14
 2.4   Object Identity                                                15
3. IPP Operations                                                     18
 3.1   Common Semantics                                               19
  3.1.1   Required Parameters                                         19
  3.1.2   Operation IDs and Request IDs                               20
  3.1.3   Attributes                                                  20
  3.1.4   Character Set and Natural Language Operation Attributes     22
   3.1.4.1  Request Operation Attributes                              22
   3.1.4.2  Response Operation Attributes                             26
  3.1.5   Operation Targets                                           28
  3.1.6   Operation Status Codes and Messages                         29
  3.1.7   Versions                                                    30
  3.1.8   Job Creation Operations                                     32
 3.2   Printer Operations                                             34
  3.2.1   Print-Job Operation                                         34
   3.2.1.1  Print-Job Request                                         34
   3.2.1.2  Print-Job Response                                        38
  3.2.2   Print-URI Operation                                         41
  3.2.3   Validate-Job Operation                                      42
  3.2.4   Create-Job Operation                                        42
  3.2.5   Get-Printer-Attributes Operation                            43
   3.2.5.1  Get-Printer-Attributes Request                            44
   3.2.5.2  Get-Printer-Attributes Response                           46
  3.2.6   Get-Jobs Operation                                          47
   3.2.6.1  Get-Jobs Request                                          47
   3.2.6.2  Get-Jobs Response                                         49
 3.3   Job Operations                                                 50
  3.3.1   Send-Document Operation                                     50
   3.3.1.1  Send-Document Request                                     51
   3.3.1.2  Send-Document Response                                    53
  3.3.2   Send-URI Operation                                          54

  3.3.3   Cancel-Job Operation                                        54
   3.3.3.1  Cancel-Job Request                                        54
   3.3.3.2  Cancel-Job Response                                       55
  3.3.4   Get-Job-Attributes Operation                                56
   3.3.4.1  Get-Job-Attributes Request                                57
   3.3.4.2  Get-Job-Attributes Response                               57
4. Object Attributes                                                  58
 4.1   Attribute Syntaxes                                             59
  4.1.1   'text'                                                      60
   4.1.1.1  'textWithoutLanguage'                                     61
   4.1.1.2  'textWithLanguage'                                        61
  4.1.2   'name'                                                      62
   4.1.2.1  'nameWithoutLanguage'                                     62
   4.1.2.2  'nameWithLanguage'                                        63
   4.1.2.3  Matching 'name' attribute values                          63
  4.1.3   'keyword'                                                   64
  4.1.4   'enum'                                                      65
  4.1.5   'uri'                                                       65
  4.1.6   'uriScheme'                                                 65
  4.1.7   'charset'                                                   66
  4.1.8   'naturalLanguage'                                           67
  4.1.9   'mimeMediaType'                                             67
  4.1.10  'octetString'                                               69
  4.1.11  'boolean'                                                   69
  4.1.12  'integer'                                                   69
  4.1.13  'rangeOfInteger'                                            69
  4.1.14  'dateTime'                                                  69
  4.1.15  'resolution'                                                69
  4.1.16  '1setOf  X'                                                 70
 4.2   Job Template Attributes                                        70
  4.2.1   job-priority (integer(1:100))                               74
  4.2.2   job-hold-until (type3 keyword | name (MAX))                 75
  4.2.3   job-sheets (type3 keyword | name(MAX))                      75
  4.2.4   multiple-document-handling (type2 keyword)                  76
  4.2.5   copies (integer(1:MAX))                                     77
  4.2.6   finishings (1setOf type2 enum)                              78
  4.2.7   page-ranges (1setOf rangeOfInteger (1:MAX))                 79
  4.2.8   sides (type2 keyword)                                       80
  4.2.9   number-up (integer(1:MAX))                                  80
  4.2.10  orientation-requested (type2 enum)                          81
  4.2.11  media (type3 keyword | name(MAX))                           82
  4.2.12  printer-resolution (resolution)                             83
  4.2.13  print-quality (type2 enum)                                  83
 4.3   Job Description Attributes                                     84
  4.3.1   job-uri (uri)                                               85
  4.3.2   job-id (integer(1:MAX))                                     85
  4.3.3   job-printer-uri (uri)                                       86
  4.3.4   job-more-info (uri)                                         86

  4.3.5   job-name (name(MAX))                                        86
  4.3.6   job-originating-user-name (name(MAX))                       86
  4.3.7   job-state (type1 enum)                                      87
  4.3.8   job-state-reasons (1setOf  type2 keyword)                   90
  4.3.9   job-state-message (text(MAX))                               92
  4.3.10  number-of-documents (integer(0:MAX))                        93
  4.3.11  output-device-assigned (name(127))                          93
  4.3.12  time-at-creation (integer(0:MAX))                           93
  4.3.13  time-at-processing (integer(0:MAX))                         93
  4.3.14  time-at-completed (integer(0:MAX))                          94
  4.3.15  number-of-intervening-jobs (integer(0:MAX))                 94
  4.3.16  job-message-from-operator (text(127))                       94
  4.3.17  job-k-octets (integer(0:MAX))                               94
  4.3.18  job-impressions (integer(0:MAX))                            95
  4.3.19  job-media-sheets (integer(0:MAX))                           95
  4.3.20  job-k-octets-processed (integer(0:MAX))                     96
  4.3.21  job-impressions-completed (integer(0:MAX))                  96
  4.3.22  job-media-sheets-completed (integer(0:MAX))                 96
  4.3.23  attributes-charset (charset)                                97
  4.3.24  attributes-natural-language (naturalLanguage)               97
 4.4   Printer Description Attributes                                 97
  4.4.1   printer-uri-supported (1setOf uri)                          99
  4.4.2   uri-security-supported (1setOf type2 keyword)              100
  4.4.3   printer-name (name(127))                                   101
  4.4.4   printer-location (text(127))                               101
  4.4.5   printer-info (text(127))                                   101
  4.4.6   printer-more-info (uri)                                    101
  4.4.7   printer-driver-installer (uri)                             102
  4.4.8   printer-make-and-model (text(127))                         102
  4.4.9   printer-more-info-manufacturer (uri)                       102
  4.4.10  printer-state (type1 enum)                                 102
  4.4.11  printer-state-reasons (1setOf type2 keyword)               103
  4.4.12  printer-state-message (text(MAX))                          106
  4.4.13  operations-supported (1setOf type2 enum)                   106
  4.4.14  charset-configured (charset)                               107
  4.4.15  charset-supported (1setOf charset)                         107
  4.4.16  natural-language-configured (naturalLanguage)              107
  4.4.17  generated-natural-language-supported(1setOf naturalLanguage108
  4.4.18  document-format-default (mimeMediaType)                    108
  4.4.19  document-format-supported (1setOf mimeMediaType)           108
  4.4.20  printer-is-accepting-jobs (boolean)                        109
  4.4.21  queued-job-count (integer(0:MAX))                          109
  4.4.22  printer-message-from-operator (text(127))                  109
  4.4.23  color-supported (boolean)                                  109
  4.4.24  reference-uri-schemes-supported (1setOf uriScheme)         109
  4.4.25  pdl-override-supported (type2 keyword)                     110
  4.4.26  printer-up-time (integer(1:MAX))                           110
  4.4.27  printer-current-time (dateTime)                            111

  4.4.28  multiple-operation-time-out (integer(1:MAX))               111
  4.4.29  compression-supported (1setOf type3 keyword)               111
  4.4.30  job-k-octets-supported (rangeOfInteger(0:MAX))             112
  4.4.31  job-impressions-supported (rangeOfInteger(0:MAX))          112
  4.4.32  job-media-sheets-supported (rangeOfInteger(0:MAX))         112
5. Conformance                                                       112
 5.1   Client Conformance Requirements                               112
 5.2   IPP Object Conformance Requirements                           113
  5.2.1   Objects                                                    113
  5.2.2   Operations                                                 113
  5.2.3   IPP Object Attributes                                      114
  5.2.4   Extensions                                                 114
  5.2.5   Attribute Syntaxes                                         115
 5.3   Charset and Natural Language Requirements                     115
 5.4   Security Conformance Requirements                             115
6. IANA Considerations (registered and private extensions)           116
 6.1   Typed 'keyword' and 'enum' Extensions                         116
 6.2   Attribute Extensibility                                       119
 6.3   Attribute Syntax Extensibility                                119
 6.4   Operation Extensibility                                       120
 6.5   Attribute Groups                                              120
 6.6   Status Code Extensibility                                     120
 6.7   Registration of MIME types/sub-types for document-formats     121
 6.8   Registration of charsets for use in 'charset' attribute values121
7. Internationalization Considerations                               121
8. Security Considerations                                           125
 8.1   Security Scenarios                                            126
  8.1.1   Client and Server in the Same Security Domain              126
  8.1.2   Client and Server in Different Security Domains            126
  8.1.3   Print by Reference                                         127
 8.2   URIs for SSL3 and non-SSL3 Access                             127
 8.3   The "requesting-user-name" (name(MAX)) Operation Attribute    127
 8.4   Restricted Queries                                            129
 8.5   Queries on jobs submitted using non-IPP protocols             129
 8.6   IPP Security Application Profile for SSL3                     130
9. References                                                        131
10. Authors' Addresses                                               134
11. Formats for IPP Registration Proposals                           136
 11.1  Type2 keyword attribute values registration                   136
 11.2  Type3 keyword attribute values registration                   137
 11.3  Type2 enum attribute values registration                      137
 11.4  Type3 enum attribute values registration                      137
 11.5  Attribute registration                                        138
 11.6  Attribute Syntax registration                                 138
 11.7  Operation registration                                        139
 11.8  Attribute Group registration                                  139
 11.9  Status code registration                                      139
12.APPENDIX A: Terminology                                           141

 12.1  Conformance Terminology                                       141
  12.1.1  NEED NOT                                                   141
 12.2  Model Terminology                                             141
  12.2.1  Keyword                                                    141
  12.2.2  Attributes                                                 141
   12.2.2.1 Attribute Name                                           141
   12.2.2.2 Attribute Group Name                                     142
   12.2.2.3 Attribute Value                                          142
   12.2.2.4 Attribute Syntax                                         142
  12.2.3  Supports                                                   142
  12.2.4  print-stream page                                          144
  12.2.5  impression                                                 144
13.APPENDIX B:  Status Codes and Suggested Status Code Messages      145
 13.1  Status Codes                                                  146
  13.1.1  Informational                                              146
  13.1.2  Successful Status Codes                                    146
   13.1.2.1 successful-ok (0x0000)                                   146
   13.1.2.2 successful-ok-ignored-or-substituted-attributes (0x0001) 146
   13.1.2.3 successful-ok-conflicting-attributes (0x0002)            147
  13.1.3  Redirection Status Codes                                   147
  13.1.4  Client Error Status Codes                                  147
   13.1.4.1 client-error-bad-request (0x0400)                        147
   13.1.4.2 client-error-forbidden (0x0401)                          147
   13.1.4.3 client-error-not-authenticated (0x0402)                  148
   13.1.4.4 client-error-not-authorized (0x0403)                     148
   13.1.4.5 client-error-not-possible (0x0404)                       148
   13.1.4.6 client-error-timeout (0x0405)                            148
   13.1.4.7 client-error-not-found (0x0406)                          149
   13.1.4.8 client-error-gone (0x0407)                               149
   13.1.4.9 client-error-request-entity-too-large (0x0408)           149
   13.1.4.10client-error-request-value-too-long (0x0409)             150
   13.1.4.11client-error-document-format-not-supported (0x040A)      150
   13.1.4.12client-error-attributes-or-values-not-supported (0x040B) 150
   13.1.4.13client-error-uri-scheme-not-supported (0x040C)           151
   13.1.4.14client-error-charset-not-supported (0x040D)              151
   13.1.4.15client-error-conflicting-attributes (0x040E)             151
  13.1.5  Server Error Status Codes                                  151
   13.1.5.1 server-error-internal-error (0x0500)                     151
   13.1.5.2 server-error-operation-not-supported (0x0501)            152
   13.1.5.3 server-error-service-unavailable (0x0502)                152
   13.1.5.4 server-error-version-not-supported (0x0503)              152
   13.1.5.5 server-error-device-error (0x0504)                       152
   13.1.5.6 server-error-temporary-error (0x0505)                    153
   13.1.5.7 server-error-not-accepting-jobs (0x0506)                 153
   13.1.5.8 server-error-busy (0x0507)                               153
   13.1.5.9 server-error-job-canceled (0x0508)                       153
 13.2  Status Codes for IPP Operations                               153
14.APPENDIX C:  "media" keyword values                               155

15.APPENDIX D: Processing IPP Attributes                             160
 15.1  Fidelity                                                      160
 15.2  Page Description Language (PDL) Override                      161
 15.3  Using Job Template Attributes During Document Processing.     163
16.APPENDIX E: Generic Directory Schema                              166
17.APPENDIX F: Change History for the Model and Semantics document   168
18.FULL COPYRIGHT STATEMENT                                          173

1. Introduction

   The Internet Printing Protocol (IPP) is an application level protocol
   that can be used for distributed printing using Internet tools and
   technologies.  IPP version 1.0 (IPP/1.0) focuses only on end user
   functionality.  This document is just one of a suite of documents
   that fully define IPP.  The full set of IPP documents includes:

     Design Goals for an Internet Printing Protocol [RFC2567]
     Rationale for the Structure and Model and Protocol for the Internet
        Printing Protocol [RFC2568]
     Internet Printing Protocol/1.0: Model and Semantics (this document)
     Internet Printing Protocol/1.0: Encoding and Transport [RFC2565]
     Internet Printing Protocol/1.0: Implementer's Guide [ipp-iig]
     Mapping between LPD and IPP Protocols [RFC2569]

   Anyone reading these documents for the first time is strongly
   encouraged to read the IPP documents in the above order.

   This document is laid out as follows:

     - The rest of Section 1 is an introduction to the IPP simplified
       model for distributed printing.
     - Section 2 introduces the object types covered in the model with
       their basic behaviors, attributes, and interactions.
     - Section 3 defines the operations included in IPP/1.0.  IPP
       operations are synchronous, therefore, for each operation, there
       is a both request and a response.
     - Section 4 defines the attributes (and their syntaxes) that are
       used in the model.
     - Sections 5 - 6 summarizes the implementation conformance
       requirements for objects that support the protocol and IANA
       considerations, respectively.
     - Sections 7 - 11 cover the Internationalization and Security
       considerations as well as References, Author contact information,
       and Formats for Registration Proposals.
     - Sections 12 - 14 are appendices that cover Terminology, Status
       Codes and Messages, and "media" keyword values.

             Note: This document uses terms such as "attributes",
             "keywords", and "support".  These terms have special
             meaning and are defined in the model terminology section
             12.2.  Capitalized terms, such as MUST, MUST NOT, REQUIRED,
             SHOULD, SHOULD NOT, MAY, NEED NOT, and OPTIONAL, have
             special meaning relating to conformance.  These terms are
             defined in section 12.1 on conformance terminology, most of
             which is taken from RFC 2119 [RFC2119].

     - Section 15 is an appendix that helps to clarify the effects of
       interactions between related attributes and their values.
     - Section 16 is an appendix that enumerates the subset of Printer
       attributes that form a generic directory schema.  These
       attributes are useful when registering a Printer so that a
       client can find the Printer not just by name, but by filtered
       searches as well.
     - Section 17 is an appendix that provides a Change History
       summarizing the clarification and changes that might affect an
       implementation since the June 30, 1998 draft.

1.1 Simplified Printing Model

   In order to achieve its goal of realizing a workable printing
   protocol for the Internet, the Internet Printing Protocol (IPP) is
   based on a simplified printing model that abstracts the many
   components of real world printing solutions.  The Internet is a
   distributed computing environment where requesters of print services
   (clients, applications, printer drivers, etc.) cooperate and interact
   with print service providers.  This model and semantics document
   describes a simple, abstract model for IPP even though the underlying
   configurations may be complex "n-tier" client/server systems.  An
   important simplifying step in the IPP model is to expose only the key
   objects and interfaces required for printing.  The model described in
   this model document does not include features, interfaces, and
   relationships that are beyond the scope of the first version of IPP
   (IPP/1.0).  IPP/1.0 incorporates many of the relevant ideas and
   lessons learned from other specification and development efforts
   [HTPP] [ISO10175] [LDPA] [P1387.4] [PSIS] [RFC1179] [SWP].  IPP is
   heavily influenced by the printing model introduced in the Document
   Printing Application (DPA) [ISO10175] standard.  Although DPA
   specifies both end user and administrative features, IPP version 1.0
   (IPP/1.0) focuses only on end user functionality.

   The IPP/1.0 model encapsulates the important components of
   distributed printing into two object types:

     - Printer (Section 2.1)
     - Job (Section 2.2)

   Each object type has an associated set of operations (see section 3)
   and attributes (see section 4).

   It is important, however, to understand that in real system
   implementations (which lie underneath the abstracted IPP/1.0 model),
   there are other components of a print service which are not
   explicitly defined in the IPP/1.0 model. The following figure
   illustrates where IPP/1.0 fits with respect to these other
   components.

                                +--------------+
                                |  Application |
                      o         +. . . . . . . |
                     \|/        |   Spooler    |
                     / \        +. . . . . . . |   +---------+
                   End-User     | Print Driver |---|  File   |
         +-----------+ +-----+  +------+-------+   +----+----+
         |  Browser  | | GUI |         |                |
         +-----+-----+ +--+--+         |                |
               |          |            |                |
               |      +---+------------+---+            |
   N   D   S   |      |      IPP Client    |------------+
   O   I   E   |      +---------+----------+
   T   R   C   |                |
   I   E   U   |
   F   C   R   -------------- Transport ------------------
   I   T   I
   C   O   T                    |         --+
   A   R   Y           +--------+--------+  |
   T   Y               |    IPP Server   |  |
   I                   +--------+--------+  |
   O                            |           |
   N                   +-----------------+  | IPP Printer
                       |  Print Service  |  |
                       +-----------------+  |
                                |         --+
                       +-----------------+
                       | Output Device(s)|
                       +-----------------+

   An IPP Printer object encapsulates the functions normally associated
   with physical output devices along with the spooling, scheduling and
   multiple device management functions often associated with a print
   server. Printer objects are optionally registered as entries in a
   directory where end users find and select them based on some sort of
   filtered and context based searching mechanism (see section 16).  The
   directory is used to store relatively static information about the
   Printer, allowing end users to search for and find Printers that

   match their search criteria, for example: name, context, printer
   capabilities, etc.  The more dynamic information, such as state,
   currently loaded and ready media, number of jobs at the Printer,
   errors, warnings, and so forth, is directly associated with the
   Printer object itself rather than with the entry in the directory
   which only represents the Printer object.

   IPP clients implement the IPP protocol on the client side and give
   end users (or programs running on behalf of end users) the ability to
   query Printer objects and submit and manage print jobs.  An IPP
   server is just that part of the Printer object that implements the
   server-side protocol.  The rest of the Printer object implements (or
   gateways into) the application semantics of the print service itself.
   The Printer objects may be embedded in an output device or may be
   implemented on a host on the network that communicates with an output
   device.

   When a job is submitted to the Printer object and the Printer object
   validates the attributes in the submission request, the Printer
   object creates a new Job object.  The end user then interacts with
   this new Job object to query its status and monitor the progress of
   the job.  End users may also cancel the print job by using the Job
   object's Cancel-Job operation.  The notification service is out of
   scope for IPP/1.0, but using such a notification service, the end
   user is able to register for and receive Printer specific and Job
   specific events.  An end user can query the status of Printer objects
   and can follow the progress of Job objects by polling using the Get-
   Printer-Attributes, Get-Jobs, and Get-Job-Attributes operations.

2. IPP Objects

   The IPP/1.0 model introduces objects of type Printer and Job.  Each
   type of object models relevant aspects of a real-world entity such as
   a real printer or real print job.  Each object type is defined as a
   set of possible attributes that may be supported by instances of that
   object type.  For each object (instance), the actual set of supported
   attributes and values describe a specific implementation.  The
   object's attributes and values describe its state, capabilities,
   realizable features, job processing functions, and default behaviors
   and characteristics.  For example, the Printer object type is defined
   as a set of attributes that each Printer object potentially supports.
   In the same manner, the Job object type is defined as a set of
   attributes that are potentially supported by each Job object.

   Each attribute included in the set of attributes defining an object
   type is labeled as:

     - "REQUIRED": each object MUST support the attribute.
     - "OPTIONAL": each object MAY support the attribute.

   There is no such similar labeling of attribute values.  However, if
   an implementation supports an attribute, it MUST support at least one
   of the possible values for that attribute.

2.1 Printer Object

   The major component of the IPP/1.0 model is the Printer object.  A
   Printer object implements the server-side of the IPP/1.0 protocol.
   Using the protocol, end users may query the attributes of the Printer
   object and submit print jobs to the Printer object.  The actual
   implementation components behind the Printer abstraction may take on
   different forms and different configurations.  However, the model
   abstraction allows the details of the configuration of real
   components to remain opaque to the end user.  Section 3 describes
   each of the Printer operations in detail.

   The capabilities and state of a Printer object are described by its
   attributes.  Printer attributes are divided into two groups:

     - "job-template" attributes: These attributes describe supported
       job processing capabilities and defaults for the Printer object.
       (See section 4.2)
     - "printer-description" attributes: These attributes describe the
       Printer object's identification, state, location, references to
       other sources of information about the Printer object, etc. (see
       section 4.4)

   Since a Printer object is an abstraction of a generic document output
   device and print service provider, a Printer object could be used to
   represent any real or virtual device with semantics consistent with
   the Printer object, such as a fax device, an imager, or even a CD
   writer.

   Some examples of configurations supporting a Printer object include:

     1) An output device with no spooling capabilities
     2) An output device with a built-in spooler
     3) A print server supporting IPP with one or more associated output
        devices
        3a) The associated output devices may or may not be capable of
          spooling jobs
        3b) The associated output devices may or may not support IPP

   The following figures show some examples of how Printer objects can
   be realized on top of various distributed printing configurations.
   The embedded case below represents configurations 1 and 2. The hosted
   and fan-out figures below represent configurations 3a and 3b.

   Legend:

   ##### indicates a Printer object which is
         either embedded in an output device or is
         hosted in a server.  The Printer object
         might or might not be capable of queuing/spooling.

   any   indicates any network protocol or direct
         connect, including IPP

   embedded printer:
                                             output device
                                           +---------------+
    O   +--------+                         |  ###########  |
   /|\  | client |------------IPP------------># Printer #  |
   / \  +--------+                         |  # Object  #  |
                                           |  ###########  |
                                           +---------------+

   hosted printer:
                                           +---------------+
    O   +--------+        ###########      |               |
   /|\  | client |--IPP--># Printer #-any->| output device |
   / \  +--------+        # Object  #      |               |
                          ###########      +---------------+

                                            +---------------+
   fan out:                                 |               |
                                        +-->| output device |
                                    any/    |               |
    O   +--------+      ###########   /     +---------------+
   /|\  | client |-IPP-># Printer #--*
   / \  +--------+      # Object  #   \     +---------------+
                        ########### any\    |               |
                                        +-->| output device |
                                            |               |
                                            +---------------+

2.2 Job Object

   A Job object is used to model a print job.  A Job object contains
   documents.  The information required to create a Job object is sent
   in a create request from the end user via an IPP Client to the
   Printer object.  The Printer object validates the create request, and
   if the Printer object accepts the request, the Printer object creates
   the new Job object.  Section 3 describes each of the Job operations
   in detail.

   The characteristics and state of a Job object are described by its
   attributes.  Job attributes are grouped into two groups as follows:

     - "job-template" attributes: These attributes can be supplied by
       the client or end user and include job processing instructions
       which are intended to override any Printer object defaults and/or
       instructions embedded within the document data. (See section 4.2)
     - "job-description" attributes: These attributes describe the Job
       object's identification, state, size, etc. The client supplies
       some of these attributes, and the Printer object generates others.
       (See section 4.3)

   An implementation MUST support at least one document per Job object.
   An implementation MAY support multiple documents per Job object.  A
   document is either:

     - a stream of document data in a format supported by the Printer
       object (typically a Page Description Language - PDL), or
     - a reference to such a stream of document data

   In IPP/1.0, a document is not modeled as an IPP object, therefore it
   has no object identifier or associated attributes.  All job
   processing instructions are modeled as Job object attributes.  These
   attributes are called Job Template attributes and they apply equally
   to all documents within a Job object.

2.3 Object Relationships

   IPP objects have relationships that are maintained persistently along
   with the persistent storage of the object attributes.

   A Printer object can represent either one or more physical output
   devices or a logical device which "processes" jobs but never actually
   uses a physical output device to put marks on paper.  Examples of
   logical devices include a Web page publisher or a gateway into an
   online document archive or repository.  A Printer object contains
   zero or more Job objects.

   A Job object is contained by exactly one Printer object, however the
   identical document data associated with a Job object could be sent to
   either the same or a different Printer object.  In this case, a
   second Job object would be created which would be almost identical to
   the first Job object, however it would have new (different) Job
   object identifiers (see section 2.4).

   A Job object is either empty (before any documents have been added)
   or contains one or more documents.  If the contained document is a
   stream of document data, that stream can be contained in only one
   document.  However, there can be identical copies of the stream in
   other documents in the same or different Job objects.  If the
   contained document is just a reference to a stream of document data,
   other documents (in the same or different Job object(s)) may contain
   the same reference.

2.4 Object Identity

   All Printer and Job objects are identified by a Uniform Resource
   Identifier (URI) [RFC2396] so that they can be persistently and
   unambiguously referenced.  The notion of a URI is a useful concept,
   however, until the notion of URI is more stable (i.e., defined more
   completely and deployed more widely), it is expected that the URIs
   used for IPP objects will actually be URLs [RFC2396].  Since every
   URL is a specialized form of a URI, even though the more generic term
   URI is used throughout the rest of this document, its usage is
   intended to cover the more specific notion of URL as well.

   An administrator configures Printer objects to either support or not
   support authentication and/or message privacy using SSL3 [SSL] (the
   mechanism for security configuration is outside the scope of
   IPP/1.0).  In some situations, both types of connections (both
   authenticated and unauthenticated) can be established using a single
   communication channel that has some sort of negotiation mechanism.
   In other situations, multiple communication channels are used, one
   for each type of security configuration.  Section 8 provides a full
   description of all security considerations and configurations.

   If a Printer object supports more than one communication channel,
   some or all of those channels might support and/or require different
   security mechanisms.  In such cases, an administrator could expose
   the simultaneous support for these multiple communication channels as
   multiple URIs for a single Printer object where each URI represents
   one of the communication channels to the Printer object. To support
   this flexibility, the IPP Printer object type defines a multi-valued
   identification attribute called the "printer-uri-supported"
   attribute.  It MUST contain at least one URI.  It MAY contain more
   than one URI.  That is, every Printer object will have at least one

   URI that identifies at least one communication channel to the Printer
   object, but it may have more than one URI where each URI identifies a
   different communication channel to the Printer object.  The
   "printer-uri-supported" attribute has a companion attribute, the
   "uri-security-supported" attribute, that has the same cardinality as
   "printer-uri-supported".  The purpose of the "uri-security-supported"
   attribute is to indicate the security mechanisms (if any) used for
   each URI listed in "printer-uri-supported".  These two attributes are
   fully described in sections 4.4.1 and 4.4.2.

   When a job is submitted to the Printer object via a create request,
   the client supplies only a single Printer object URI.  The client
   supplied Printer object URI MUST be one of the values in the
   "printer-uri-supported" Printer attribute.

   Note:  IPP/1.0 does not specify how the client obtains the client
   supplied URI, but it is RECOMMENDED that a Printer object be
   registered as an entry in a directory service.  End-users and
   programs can then interrogate the directory searching for Printers.
   Section 16 defines a generic schema for Printer object entries in the
   directory service and describes how the entry acts as a bridge to the
   actual IPP Printer object.  The entry in the directory that
   represents the IPP Printer object includes the possibly many URIs for
   that Printer object as values in one its attributes.

   When a client submits a create request to the Printer object, the
   Printer object validates the request and creates a new Job object.
   The Printer object assigns the new Job object a URI which is stored
   in the "job-uri" Job attribute.  This URI is then used by clients as
   the target for subsequent Job operations.  The Printer object
   generates a Job URI based on its configured security policy and the
   URI used by the client in the create request.

   For example, consider a Printer object that supports both a
   communication channel secured by the use of SSL3 (using HTTP over
   SSL3 with an "https" schemed URI) and another open communication
   channel that is not secured with SSL3 (using a simple "http" schemed
   URI).  If a client were to submit a job using the secure URI, the
   Printer object would assign the new Job object a secure URI as well.
   If a client were to submit a job using the open-channel URI, the
   Printer would assign the new Job object an open-channel URI.

   In addition, the Printer object also populates the Job object's
   "job-printer-uri" attribute.  This is a reference back to the Printer
   object that created the Job object.  If a client only has access to a
   Job object's "job-uri" identifier, the client can query the Job's
   "job-printer-uri" attribute in order to determine which Printer
   object created the Job object.  If the Printer object supports more

   than one URI, the Printer object picks the one URI supplied by the
   client when creating the job to build the value for and to populate
   the Job's "job-printer-uri" attribute.

   Allowing Job objects to have URIs allows for flexibility and
   scalability.  For example, in some implementations, the Printer
   object might create Jobs that are processed in the same local
   environment as the Printer object itself.  In this case, the Job URI
   might just be a composition of the Printer's URI and some unique
   component for the Job object, such as the unique 32-bit positive
   integer mentioned later in this paragraph.  In other implementations,
   the Printer object might be a central clearing-house for validating
   all Job object creation requests, but the Job object itself might be
   created in some environment that is remote from the Printer object.
   In this case, the Job object's URI may have no physical-location
   relationship at all to the Printer object's URI.  Again, the fact
   that Job objects have URIs allows for flexibility and scalability,
   however, many existing printing systems have local models or
   interface constraints that force print jobs to be identified using
   only a 32-bit positive integer rather than an independent URI.  This
   numeric Job ID is only unique within the context of the Printer
   object to which the create request was originally submitted.
   Therefore, in order to allow both types of client access to IPP Job
   objects (either by Job URI or by numeric Job ID), when the Printer
   object successfully processes a create request and creates a new Job
   object, the Printer object MUST generate both a Job URI and a Job ID.
   The Job ID (stored in the "job-id" attribute) only has meaning in the
   context of the Printer object to which the create request was
   originally submitted. This requirement to support both Job URIs and
   Job IDs allows all types of clients to access Printer objects and Job
   objects no matter the local constraints imposed on the client
   implementation.

   In addition to identifiers, Printer objects and Job objects have
   names ("printer-name" and "job-name").  An object name NEED NOT be
   unique across all instances of all objects. A Printer object's name
   is chosen and set by an administrator through some mechanism outside
   the scope of IPP/1.0.  A Job object's name is optionally chosen and
   supplied by the IPP client submitting the job.  If the client does
   not supply a Job object name, the Printer object generates a name for
   the new Job object.  In all cases, the name only has local meaning.

   To summarize:

     - Each Printer object is identified with one or more URIs.  The
       Printer's "printer-uri-supported" attribute contains the URI(s).

     - The Printer object's "uri-security-supported" attribute
       identifies the communication channel security protocols that may
       or may not have been configured for the various Printer object
       URIs (e.g., 'ssl3' or 'none').
     - Each Job object is identified with a Job URI.  The Job's "job-uri"
       attribute contains the URI.
     - Each Job object is also identified with Job ID which is a 32-bit,
       positive integer.  The Job's "job-id" attribute contains the Job
       ID.  The Job ID is only unique within the context of the Printer
       object  which created the Job object.
     - Each Job object has a "job-printer-uri" attribute which contains
       the URI of the Printer object that was used to create the Job
       object.  This attribute is used to determine the Printer object
       that created a Job object when given only the URI for the Job
       object.  This linkage is necessary to determine the languages,
       charsets, and operations which are supported on that Job (the
       basis for such support comes from the creating Printer object).
     - Each Printer object has a name (which is not necessarily unique).
       The administrator chooses and sets this name through some
       mechanism outside the scope of IPP/1.0 itself.  The Printer
       object's "printer-name" attribute contains the name.
     - Each Job object has a name (which is not necessarily unique).  The
       client optionally supplies this name in the create request.  If
       the client does not supply this name, the Printer object generates
       a name for the Job object. The Job object's "job-name" attribute
       contains the name.

3. IPP Operations

   IPP objects support operations.  An operation consists of a request
   and a response.  When a client communicates with an IPP object, the
   client issues an operation request to the URI for that object.
   Operation requests and responses have parameters that identify the
   operation.  Operations also have attributes that affect the run-time
   characteristics of the operation (the intended target, localization
   information, etc.).  These operation-specific attributes are called
   operation attributes (as compared to object attributes such as
   Printer object attributes or Job object attributes).  Each request
   carries along with it any operation attributes, object attributes,
   and/or document data required to perform the operation.  Each request
   requires a response from the object.  Each response indicates success
   or failure of the operation with a status code as a response
   parameter.  The response contains any operation attributes, object
   attributes, and/or status messages generated during the execution of
   the operation request.

   This section describes the semantics of the IPP operations, both
   requests and responses, in terms of the parameters, attributes, and
   other data associated with each operation.

   The IPP/1.0 Printer operations are:

     Print-Job (section 3.2.1)
     Print-URI (section 3.2.2)
     Validate-Job (section 3.2.3)
     Create-Job (section 3.2.4)
     Get-Printer-Attributes (section 3.2.5)
     Get-Jobs (section 3.2.6)

   The Job operations are:

     Send-Document (section 3.3.1)
     Send-URI (section 3.3.2)
     Cancel-Job (section 3.3.3)
     Get-Job-Attributes (section 3.3.4)

   The Send-Document and Send-URI Job operations are used to add a new
   document to an existing multi-document Job object created using the
   Create-Job operation.

3.1 Common Semantics

   All IPP operations require some common parameters and operation
   attributes.  These common elements and their semantic characteristics
   are defined and described in more detail in the following sections.

3.1.1 Required Parameters

   Every operation request contains the following REQUIRED parameters:

     - a "version-number",
     - an "operation-id",
     - a "request-id", and
     - the attributes that are REQUIRED for that type of request.

   Every operation response contains the following REQUIRED parameters:

     - a "version-number",
     - a "status-code",
     - the "request-id" that was supplied in the corresponding request,
        and
     - the attributes that are REQUIRED for that type of response.

   The encoding and transport document [RFC2565] defines special rules
   for the encoding of these parameters.  All other operation elements
   are represented using the more generic encoding rules for attributes
   and groups of attributes.

3.1.2 Operation IDs and Request IDs

   Each IPP operation request includes an identifying "operation-id"
   value.  Valid values are defined in the "operations-supported"
   Printer attribute section (see section 4.4.13).  The client specifies
   which operation is being requested by supplying the correct
   "operation-id" value.

   In addition, every invocation of an operation is identified by a
   "request-id" value. For each request, the client chooses the
   "request-id" which MUST be an integer (possibly unique depending on
   client requirements) in the range from 1 to 2**31 - 1 (inclusive).
   This "request-id" allows clients to manage multiple outstanding
   requests. The receiving IPP object copies all 32-bits of the client-
   supplied "request-id" attribute into the response so that the client
   can match the response with the correct outstanding request, even if
   the "request-id" is out of range.  If the request is terminated
   before the complete "request-id" is received, the IPP object rejects
   the request and returns a response with a "request-id" of 0.

   Note: In some cases, the transport protocol underneath IPP might be a
   connection oriented protocol that would make it impossible for a
   client to receive responses in any order other than the order in
   which the corresponding requests were sent.  In such cases, the
   "request-id" attribute would not be essential for correct protocol
   operation.  However, in other mappings, the operation responses can
   come back in any order.  In these cases, the "request-id" would be
   essential.

3.1.3 Attributes

   Operation requests and responses are both composed of groups of
   attributes and/or document data.  The attributes groups are:

     - Operation Attributes: These attributes are passed in the
       operation and affect the IPP object's behavior while processing
       the operation request and may affect other attributes or groups
       of attributes.  Some operation attributes describe the document
       data associated with the print job and are associated with new
       Job objects, however most operation attributes do not persist
       beyond the life of the operation.  The description of each
       operation attribute includes conformance statements indicating
       which operation attributes are REQUIRED and which are OPTIONAL

       for an IPP object to support and which attributes a client MUST
       supply in a request and an IPP object MUST supply in a response.
     - Job Template Attributes: These attributes affect the processing
       of a job.  A client OPTIONALLY supplies Job Template Attributes
       in a create request, and the receiving object MUST be prepared to
       receive all supported attributes.  The Job object can later be
       queried to find out what Job Template attributes were originally
       requested in the create request, and such attributes are returned
       in the response as Job Object Attributes.  The Printer object can
       be queried about its Job Template attributes to find out what
       type of job processing capabilities are supported and/or what the
       default job processing behaviors are, though such attributes are
       returned in the response as Printer Object Attributes.  The
       "ipp-attribute-fidelity" operation attribute affects processing
       of all client-supplied Job Template attributes (see section 15
       for a full description of "ipp-attribute-fidelity" and its
       relationship to other attributes).
     - Job Object Attributes: These attributes are returned in response
       to a query operation directed at a Job object.
     - Printer Object Attributes: These attributes are returned in
       response to a query operation directed at a Printer object.
     - Unsupported Attributes: In a create request, the client supplies
       a set of Operation and Job Template attributes.  If any of these
       attributes or their values is unsupported by the Printer object,
       the Printer object returns the set of unsupported attributes in
       the response.  Section 15 gives a full description of how Job
       Template attributes supplied by the client in a create request
       are processed by the Printer object and how unsupported
       attributes are returned to the client.  Because of extensibility,
       any IPP object might receive a request that contains new or
       unknown attributes or values for which it has no support. In such
       cases, the IPP object processes what it can and returns the
       unsupported attributes in the response.

   Later in this section, each operation is formally defined by
   identifying the allowed and expected groups of attributes for each
   request and response.  The model identifies a specific order for each
   group in each request or response, but the attributes within each
   group may be in any order, unless specified otherwise.

   Each attribute specification includes the attribute's name followed
   by the name of its attribute syntax(es) in parenthesizes.  In
   addition, each 'integer' attribute is followed by the allowed range
   in parentheses, (m:n), for values of that attribute.  Each 'text' or
   'name' attribute is followed by the maximum size in octets in
   parentheses, (size), for values of that attribute. For more details
   on attribute syntax notation, see the descriptions of these
   attributes syntaxes in section 4.1.

   Note: Document data included in the operation is not strictly an
   attribute, but it is treated as a special attribute group for
   ordering purposes.  The only operations that support supplying the
   document data within an operation request are Print-Job and Send-
   Document.  There are no operation responses that include document
   data.

   Note: Some operations are REQUIRED for IPP objects to support; the
   others are OPTIONAL (see section 5.2.2).  Therefore, before using an
   OPTIONAL operation, a client SHOULD first use the REQUIRED Get-
   Printer-Attributes operation to query the Printer's "operations-
   supported" attribute in order to determine which OPTIONAL Printer and
   Job operations are actually supported.  The client SHOULD NOT use an
   OPTIONAL operation that is not supported.  When an IPP object
   receives a request to perform an operation it does not support, it
   returns the 'server-error-operation-not-supported' status code (see
   section 13.1.5.2).  An IPP object is non-conformant if it does not
   support a REQUIRED operation.

3.1.4 Character Set and Natural Language Operation Attributes

   Some Job and Printer attributes have values that are text strings and
   names intended for human understanding rather than machine
   understanding (see the 'text' and 'name' attribute syntax
   descriptions in section 4.1).  The following sections describe two
   special Operation Attributes called "attributes-charset" and
   "attributes-natural-language".  These attributes are always part of
   the Operation Attributes group.  For most attribute groups, the order
   of the attributes within the group is not important.  However, for
   these two attributes within the Operation Attributes group, the order
   is critical.  The "attributes-charset" attribute MUST be the first
   attribute in the group and the "attributes-natural-language"
   attribute MUST be the second attribute in the group.  In other words,
   these attributes MUST be supplied in every IPP request and response,
   they MUST come first in the group, and MUST come in the specified
   order.  For job creation operations, the IPP Printer implementation
   saves these two attributes with the new Job object as Job Description
   attributes.  For the sake of brevity in this document, these
   operation attribute descriptions are not repeated with every
   operation request and response, but have a reference back to this
   section instead.

3.1.4.1 Request Operation Attributes

   The client MUST supply and the Printer object MUST support the
   following REQUIRED operation attributes in every IPP/1.0 operation
   request:

     "attributes-charset" (charset):
        This operation attribute identifies the charset (coded character
        set and encoding method) used by any 'text' and 'name'
        attributes that the client is supplying in this request.  It
        also identifies the charset that the Printer object MUST use (if
        supported) for all 'text' and 'name' attributes and status
        messages that the Printer object returns in the response to this
        request. See Sections 4.1.1 and 4.1.2 for the specification of
        the 'text' and 'name' attribute syntaxes.

        All clients and IPP objects MUST support the 'utf-8' charset
        [RFC2279] and MAY support additional charsets provided that they
        are registered with IANA [IANA-CS].  If the Printer object does
        not support the client supplied charset value, the Printer
        object MUST reject the request, set the "attributes-charset" to
        'utf-8' in the response, and return the 'client-error-charset-
        not-supported' status code and any 'text' or 'name' attributes
        using the 'utf-8' charset.  The Printer object MUST indicate the
        charset(s) supported as the values of the "charset-supported"
        Printer attribute (see Section 4.4.15), so that the client can
        query to determine which charset(s) are supported.

        Note to client implementers: Since IPP objects are only required
        to support the 'utf-8' charset, in order to maximize
        interoperability with multiple IPP object implementations, a
        client may want to supply 'utf-8' in the "attributes-charset"
        operation attribute, even though the client is only passing and
        able to present a simpler charset, such as US-ASCII or ISO-
        8859-1.  Then the client will have to filter out (or charset
        convert) those characters that are returned in the response that
        it cannot present to its user.  On the other hand, if both the
        client and the IPP objects also support a charset in common
        besides utf-8, the client may want to use that charset in order
        to avoid charset conversion or data loss.

        See the 'charset' attribute syntax description in Section 4.1.7
        for the syntax and semantic interpretation of the values of this
        attribute and for example values.

     "attributes-natural-language" (naturalLanguage):
        This operation attribute identifies the natural language used by
        any 'text' and 'name' attributes that the client is supplying in
        this request.  This attribute also identifies the natural
        language that the Printer object SHOULD use for all 'text' and '
        name' attributes and status messages that the Printer object
        returns in the response to this request.

        There are no REQUIRED natural languages required for the Printer
        object to support.  However, the Printer object's "generated-
        natural-language-supported" attribute identifies the natural
        languages supported by the Printer object and any contained Job
        objects for all text strings generated by the IPP object.  A
        client MAY query this attribute to determine which natural
        language(s) are supported for generated messages.

        For any of the attributes for which the Printer object generates
        text, i.e., for the "job-state-message", "printer-state-
        message", and status messages (see Section 3.1.6), the Printer
        object MUST be able to generate these text strings in any of its
        supported natural languages.  If the client requests a natural
        language that is not supported, the Printer object MUST return
        these generated messages in the Printer's configured natural
        language as specified by the Printer's "natural-language-
        configured" attribute" (see Section 4.4.16).

        For other 'text' and 'name' attributes supplied by the client,
        authentication system, operator, system administrator, or
        manufacturer (i.e., for "job-originating-user-name", "printer-
        name" (name), "printer-location" (text), "printer-info" (text),
        and "printer-make-and-model" (text)), the Printer object is only
        required to support the configured natural language of the
        Printer identified by the Printer object's "natural-language-
        configured" attribute, though support of additional natural
        languages for these attributes is permitted.

        For any 'text' or 'name' attribute in the request that is in a
        different natural language than the value supplied in the
        "attributes-natural-language" operation attribute, the client
        MUST use the Natural Language Override mechanism (see sections
        4.1.1.2 and 4.1.2.2) for each such attribute value supplied.
        The client MAY use the Natural Language Override mechanism
        redundantly, i.e., use it even when the value is in the same
        natural language as the value supplied in the "attributes-
        natural-language" operation attribute of the request.

        The IPP object MUST accept any natural language and any Natural
        Language Override, whether the IPP object supports that natural
        language or not (and independent of the value of the "ipp-
        attribute-fidelity" Operation attribute).  That is the IPP
        object accepts all client supplied values no matter what the
        values are in the Printer object's "generated-natural-language-
        supported" attribute.  That attribute, "generated-natural-
        language-supported", only applies to generated messages,

        not client supplied messages.  The IPP object MUST remember that
        natural language for all client-supplied attributes, and when
        returning those attributes in response to a query, the IPP
        object MUST indicate that natural language.

        Each value whose attribute syntax type is 'text' or 'name' (see
        sections 4.1.1 and 4.1.2) has an Associated Natural-Language.
        This document does not specify how this association is stored in
        a Printer or Job object.  When such a value is encoded in a
        request or response, the natural language is either implicit or
        explicit:

             - In the implicit case, the value contains only the
               text/name value, and the language is specified by the
               "attributes-natural-language" operation attribute in the
               request or response (see sections 4.1.1.1
               textWithoutLanguage and 4.1.2.1 nameWithoutLanguage).

             - In the explicit case (also known as the Natural-Language
               Override case), the value contains both the language and
               the text/name value (see sections 4.1.1.2
               textWithLanguage and 4.1.2.2 nameWithLanguage).

        For example, the "job-name" attribute MAY be supplied by the
        client in a create request.  The text value for this attribute
        will be in the natural language identified by the "attribute-
        natural-language" attribute, or if different, as identified by
        the Natural Language Override mechanism.  If supplied, the IPP
        object will use the value of the "job-name" attribute to
        populate the Job object's "job-name" attribute.  Whenever any
        client queries the Job object's "job-name" attribute, the IPP
        object returns the attribute as stored and uses the Natural
        Language Override mechanism to specify the natural language, if
        it is different from that reported in the "attributes-natural-
        language" operation attribute of the response.  The IPP object
        MAY use the Natural Language Override mechanism redundantly,
        i.e., use it even when the value is in the same natural language
        as the value supplied in the "attributes-natural-language"
        operation attribute of the response.

        An IPP object MUST NOT reject a request based on a supplied
        natural language in an "attributes-natural-language" Operation
        attribute or in any attribute that uses the Natural Language
        Override.

        See the 'naturalLanguage' attribute syntax description in
        section 4.1.8 for the syntax and semantic interpretation of the
        values of this attribute and for example values.

   Clients SHOULD NOT supply 'text' or 'name' attributes that use an
   illegal combination of natural language and charset.  For example,
   suppose a Printer object supports charsets 'utf-8', 'iso-8859-1', and
   'iso-8859-7'.  Suppose also, that it supports natural languages 'en'
   (English), 'fr' (French), and 'el' (Greek).  Although the Printer
   object supports the charset 'iso-8859-1' and natural language 'el',
   it probably does not support the combination of Greek text strings
   using the 'iso-8859-1' charset.  The Printer object handles this
   apparent incompatibility differently depending on the context in
   which it occurs:

     - In a create request: If the client supplies a text or name
       attribute (for example, the "job-name" operation attribute) that
       uses an apparently incompatible combination, it is a client
       choice that does not affect the Printer object or its correct
       operation.  Therefore, the Printer object simply accepts the
       client supplied value, stores it with the Job object, and
       responds back with the same combination whenever the client (or
       any client) queries for that attribute.
     - In a query-type operation, like Get-Printer-Attributes: If the
       client requests an apparently incompatible combination, the
       Printer object responds (as described in section 3.1.4.2) using
       the Printer's configured natural language rather than the natural
       language requested by the client.

   In either case, the Printer object does not reject the request
   because of the apparent incompatibility.  The potential incompatible
   combination of charset and natural language can occur either at the
   global operation level or at the Natural Language Override
   attribute-by-attribute level.  In addition, since the response always
   includes explicit charset and natural language information, there is
   never any question or ambiguity in how the client interprets the
   response.

3.1.4.2 Response Operation Attributes

   The Printer object MUST supply and the client MUST support the
   following REQUIRED operation attributes in every IPP/1.0 operation
   response:

     "attributes-charset" (charset):
        This operation attribute identifies the charset used by any '
        text' and 'name' attributes that the Printer object is returning
        in this response.  The value in this response MUST be the same
        value as the "attributes-charset" operation attribute supplied
        by the client in the request.  If this is not possible

        (i.e., the charset requested is not supported), the request
        would have been rejected.  See "attributes-charset" described in
        Section 3.1.4.1 above.

        If the Printer object supports more than just the 'utf-8'
        charset, the Printer object MUST be able to code convert between
        each of the charsets supported on a highest fidelity possible
        basis in order to return the 'text' and 'name' attributes in the
        charset requested by the client.  However, some information loss
        MAY occur during the charset conversion depending on the
        charsets involved.  For example, the Printer object may convert
        from a UTF-8 'a' to a US-ASCII 'a' (with no loss of
        information), from an ISO Latin 1 CAPITAL LETTER A WITH ACUTE
        ACCENT to US-ASCII 'A' (losing the accent), or from a UTF-8
        Japanese Kanji character to some ISO Latin 1 error character
        indication such as '?', decimal code equivalent, or to the
        absence of a character, depending on implementation.

        Note: Whether an implementation that supports more than one
        charset stores the data in the charset supplied by the client or
        code converts to one of the other supported charsets, depends on
        implementation.  The strategy should try to minimize loss of
        information during code conversion.  On each response, such an
        implementation converts from its internal charset to that
        requested.

     "attributes-natural-language" (naturalLanguage):
        This operation attribute identifies the natural language used by
        any 'text' and 'name' attributes that the IPP object is
        returning in this response.  Unlike the "attributes-charset"
        operation attribute, the IPP object NEED NOT return the same
        value as that supplied by the client in the request.  The IPP
        object MAY return the natural language of the Job object or the
        Printer's configured natural language as identified by the
        Printer object's "natural-language-configured" attribute, rather
        than the natural language supplied by the client.  For any '
        text' or 'name' attribute or status message in the response that
        is in a different natural language than the value returned in
        the "attributes-natural-language" operation attribute, the IPP
        object MUST use the Natural Language Override mechanism (see
        sections 4.1.1.2 and 4.1.2.2) on each attribute value returned.
        The IPP object MAY use the Natural Language Override mechanism
        redundantly, i.e., use it even when the value is in the same
        natural language as the value supplied in the "attributes-
        natural-language" operation attribute of the response.

3.1.5 Operation Targets

   All IPP operations are directed at IPP objects.  For Printer
   operations, the operation is always directed at a Printer object
   using one of its URIs (i.e., one of the values in the Printer
   object's "printer-uri-supported" attribute).  Even if the Printer
   object supports more than one URI, the client supplies only one URI
   as the target of the operation.  The client identifies the target
   object by supplying the correct URI in the "printer-uri (uri)"
   operation attribute.

   For Job operations, the operation is directed at either:

     - The Job object itself using the Job object's URI.  In this case,
       the client identifies the target object by supplying the correct
       URI in the "job-uri (uri)" operation attribute.
     - The Printer object that created the Job object using both the
       Printer objects URI and the Job object's Job ID.  Since the
       Printer object that created the Job object generated the Job ID,
       it MUST be able to correctly associate the client supplied Job ID
       with the correct Job object.  The client supplies the Printer
       object's URI in the "printer-uri (uri)" operation attribute and
       the Job object's Job ID in the "job-id (integer(1:MAX))"
       operation attribute.

   If the operation is directed at the Job object directly using the Job
   object's URI, the client MUST NOT include the redundant "job-id"
   operation attribute.

   The operation target attributes are REQUIRED operation attributes
   that MUST be included in every operation request.  Like the charset
   and natural language attributes (see section 3.1.4), the operation
   target attributes are specially ordered operation attributes.  In all
   cases, the operation target attributes immediately follow the
   "attributes-charset" and "attributes-natural-language" attributes
   within the operation attribute group, however the specific ordering
   rules are:

     - In the case where there is only one operation target attribute
       (i.e., either only the "printer-uri" attribute or only the "job-
       uri" attribute), that attribute MUST be the third attribute in
       the operation attributes group.
     - In the case where Job operations use two operation target
       attributes (i.e., the "printer-uri" and "job-id" attributes), the
       "printer-uri" attribute MUST be the third attribute and the
       "job-id" attribute MUST be the fourth attribute.

   In all cases, the target URIs contained within the body of IPP
   operation requests and responses must be in absolute format rather
   than relative format (a relative URL identifies a resource with the
   scope of the HTTP server, but does not include scheme, host or port).

   The following rules apply to the use of port numbers in URIs that
   identify IPP objects:

     1. If the URI scheme allows the port number to be explicitly
        included in the URI string, and a port number is specified
        within the URI, then that port number MUST be used by the client
        to contact the IPP object.

     2. If the URI scheme allows the port number to be explicitly
        included in the URI string, and a port number is not specified
        within the URI, then default port number implied by that URI
        scheme MUST be used by the client to contact the IPP object.

     3. If the URI scheme does not allow an explicit port number to be
        specified within the URI, then the default port number implied
        by that URI MUST be used by the client to contact the IPP
        object.

   Note: The IPP encoding and transport document [RFC2565] shows a
   mapping of IPP onto HTTP/1.1 and defines a new default port number
   for using IPP over HTTP/1.1.

3.1.6 Operation Status Codes and Messages

   Every operation response includes a REQUIRED "status-code" parameter
   and an OPTIONAL "status-message" operation attribute.  The "status-
   code" provides information on the processing of a request.  A
   "status-message" attribute provides a short textual description of
   the status of the operation.  The status code is intended for use by
   automata, and the status message is intended for the human end user.
   If a response does include a "status-message" attribute, an IPP
   client NEED NOT examine or display the message, however it SHOULD do
   so in some implementation specific manner.

   The "status-code" value is a numeric value that has semantic meaning.
   The "status-code" syntax is similar to a "type2 enum" (see section
   4.1 on "Attribute Syntaxes") except that values can range only from
   0x0000 to 0x7FFF.  Section 13 describes the status codes, assigns the
   numeric values, and suggests a corresponding status message for each
   status code.  The "status-message" attribute's syntax is "text(255)".
   A client implementation of IPP SHOULD convert status code values into
   any localized message that has semantic meaning to the end user.

   If the Printer object supports the "status-message" operation
   attribute, the Printer object MUST be able to generate this message
   in any of the natural languages identified by the Printer object's
   "generated-natural-language-supported" attribute (see the
   "attributes-natural-language" operation attribute specified in
   section 3.1.4.1).  As described in section 3.1.4.1 for any returned '
   text' attribute, if there is a choice for generating this message,
   the Printer object uses the natural language indicated by the value
   of the "attributes-natural-language" in the client request if
   supported, otherwise the Printer object uses the value in the Printer
   object's own "natural-language-configured" attribute.  If the Printer
   object supports the "status-message" operation attribute, it SHOULD
   use the REQUIRED 'utf-8' charset to return a status message for the
   following error status codes (see section 13): 'client-error-bad-
   request', 'client-error-charset-not-supported', 'server-error-
   internal-error', 'server-error-operation-not-supported', and '
   server-error-version-not-supported'.  In this case, it MUST set the
   value of the "attributes-charset" operation attribute to 'utf-8' in
   the error response.

3.1.7 Versions

   Each operation request and response carries with it a "version-
   number" parameter.  Each value of the "version-number" is in the form
   "X.Y" where X is the major version number and Y is the minor version
   number.  By including a version number in the client request, it
   allows the client  to identify which version of IPP it is interested
   in using.  If the IPP object does not support that version, the
   object responds with a status code of 'server-error-version-not-
   supported' along with the closest version number that is supported
   (see section 13.1.5.4).

   There is no version negotiation per se.  However, if after receiving
   a 'server-error-version-not-supported' status code from an IPP
   object, there is nothing that prevents a client from trying again
   with a different version number. In order to conform to IPP/1.0, an
   implementation MUST support at least version '1.0'.

   There is only one notion of "version number" that covers both IPP
   Model and IPP Protocol changes. Thus the version number MUST change
   when introducing a new version of the Model and Semantics document
   [RFC2566] or a new version of the Encoding and Transport document
   [RFC2565].

   Changes to the major version number indicate structural or syntactic
   changes that make it impossible for older version of IPP clients and
   Printer objects to correctly parse and process the new or changed
   attributes, operations and responses.  If the major version number

   changes, the minor version numbers is set to zero.  As an example,
   adding the "ipp-attribute-fidelity" attribute (if it had not been
   part of version '1.0'), would have required a change to the major
   version number.  Items that might affect the changing of the major
   version number include any changes to the Model and Semantics
   document [RFC2566] or the Encoding and Transport [RFC2565] itself,
   such as:

     - reordering of ordered attributes or attribute sets
     - changes to the syntax of existing attributes
     - changing Operation or Job Template attributes from OPTIONAL to
       REQUIRED and vice versa
     - adding REQUIRED (for an IPP object to support) operation
       attributes
     - adding REQUIRED (for an IPP object to support) operation
       attribute groups
     - adding values to existing operation attributes
     - adding REQUIRED operations

   Changes to the minor version number indicate the addition of new
   features, attributes and attribute values that may not be understood
   by all IPP objects, but which can be ignored if not understood.
   Items that might affect the changing of the minor version number
   include any changes to the model objects and attributes but not the
   encoding and transport rules [RFC2565] (except adding attribute
   syntaxes).  Examples of such changes are:

     - grouping all extensions not included in a previous version into
       a new version
     - adding new attribute values
     - adding new object attributes
     - adding OPTIONAL (for an IPP object to support) operation
       attributes (i.e., those attributes that an IPP object can ignore
       without confusing clients)
     - adding OPTIONAL (for an IPP object to support) operation
       attribute groups (i.e., those attributes that an IPP object can
       ignore without confusing clients)
     - adding new attribute syntaxes
     - adding OPTIONAL operations
     - changing Job Description attributes or Printer Description
       attributes from OPTIONAL to REQUIRED or vice versa.

   The encoding of the "operation-id", the "version-number", the
   "status-code", and the "request-id" MUST NOT change over any version
   number (either major or minor).  This rule guarantees that all future
   versions will be backwards compatible with all previous versions (at
   least for checking the "operation-id", the "version-number", and the
   "request-id").  In addition, any protocol elements (attributes, error

   codes, tags, etc.) that are not carried forward from one version to
   the next are deprecated so that they can never be reused with new
   semantics.

   Implementations that support a certain major version NEED NOT support
   ALL previous versions.  As each new major version is defined (through
   the release of a new specification), that major version will specify
   which previous major versions MUST be supported in compliant
   implementations.

3.1.8 Job Creation Operations

   In order to "submit a print job" and create a new Job object, a
   client issues a create request.  A create request is any one of
   following three operation requests:

     - The Print-Job Request: A client that wants to submit a print job
       with only a single document uses the Print-Job operation.  The
       operation allows for the client to "push" the document data to
       the Printer object by including the document data in the request
       itself.

     - The Print-URI Request: A client that wants to submit a print job
       with only a single document (where the Printer object "pulls" the
       document data instead of the client "pushing" the data to the
       Printer object) uses the Print-URI operation.   In this case, the
       client includes in the request only a URI reference to the
       document data (not the document data itself).

     - The Create-Job Request: A client that wants to submit a print job
       with multiple documents uses the Create-Job operation.  This
       operation is followed by an arbitrary number of Send-Document
       and/or Send-URI operations (each creating another document for
       the newly create Job object).  The Send-Document operation
       includes the document data in the request (the client "pushes"
       the document data to the printer), and the Send-URI operation
       includes only a URI reference to the document data in the request
       (the Printer "pulls" the document data from the referenced
       location).  The last Send-Document or Send-URI request for a
       given Job object includes a "last-document" operation attribute
       set to 'true' indicating that this is the last request.

   Throughout this model specification, the term "create request" is
   used to refer to any of these three operation requests.

   A Create-Job operation followed by only one Send-Document operation
   is semantically equivalent to a Print-Job operation, however, for
   performance reasons, the client SHOULD use the Print-Job operation

   for all single document jobs.  Also, Print-Job is a REQUIRED
   operation (all implementations MUST support it) whereas Create-Job is
   an OPTIONAL operation, hence some implementations might not support
   it.

   Job submission time is the point in time when a client issues a
   create request.  The initial state of every Job object is the '
   pending' or 'pending-held' state.  Later, the Printer object begins
   processing the print job.  At this point in time, the Job object's
   state moves to 'processing'.  This is known as job processing time.
   There are validation checks that must be done at job submission time
   and others that must be performed at job processing time.

   At job submission time and at the time a Validate-Job operation is
   received, the Printer MUST do the following:

     1. Process the client supplied attributes and either accept or
        reject the request
     2. Validate the syntax of and support for the scheme of any client
        supplied URI

   At job submission time the Printer object MUST validate whether or
   not the supplied attributes, attribute syntaxes, and values are
   supported by matching them with the Printer object's corresponding
   "xxx-supported" attributes.  See section 3.2.1.2 for details.  [ipp-
   iig] presents suggested steps for an IPP object to either accept or
   reject any request and additional steps for processing create
   requests.

   At job submission time the Printer object NEED NOT perform the
   validation checks reserved for job processing time such as:

     1. Validating the document data
     2. Validating the actual contents of any client supplied URI
        (resolve the reference and follow the link to the document data)

   At job submission time, these additional job processing time
   validation checks are essentially useless, since they require
   actually parsing and interpreting the document data, are not
   guaranteed to be 100% accurate, and MUST be done, yet again, at job
   processing time.  Also, in the case of a URI, checking for
   availability at job submission time does not guarantee availability
   at job processing time.   In addition, at job processing time, the
   Printer object might discover any of the following conditions that
   were not detectable at job submission time:

     - runtime errors in the document data,
     - nested document data that is in an unsupported format,

     - the URI reference is no longer valid (i.e., the server hosting
       the document might be down), or
     - any other job processing error

   At job processing time, since the Printer object has already
   responded with a successful status code in the response to the create
   request, if the Printer object detects an error, the Printer object
   is unable to inform the end user of the error with an operation
   status code.   In this case, the Printer, depending on the error, can
   set the "job-state", "job-state-reasons", or "job-state-message"
   attributes to the appropriate value(s) so that later queries can
   report the correct job status.

   Note: Asynchronous notification of events is outside the scope of
   IPP/1.0.

3.2 Printer Operations

   All Printer operations are directed at Printer objects.  A client
   MUST always supply the "printer-uri" operation attribute in order to
   identify the correct target of the operation.

3.2.1 Print-Job Operation

   This REQUIRED operation allows a client to submit a print job with
   only one document and supply the document data (rather than just a
   reference to the data).  See Section 15 for the suggested steps for
   processing create operations and their Operation and Job Template
   attributes.

3.2.1.1 Print-Job Request

   The following groups of attributes are supplied as part of the
   Print-Job Request:

   Group 1: Operation Attributes

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.1.  The Printer object
        MUST copy these values to the corresponding Job Description
        attributes described in sections 4.3.23 and 4.3.24.

     Target:
        The "printer-uri" (uri) operation attribute which is the target
        for this operation as described in section 3.1.5.

     Requesting User Name:
        The "requesting-user-name" (name(MAX)) attribute SHOULD be
        supplied by the client as described in section 8.3.

     "job-name" (name(MAX)):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  It contains the client
        supplied Job name.  If this attribute is supplied by the client,
        its value is used for the "job-name" attribute of the newly
        created Job object.  The client MAY automatically include any
        information that will help the end-user distinguish amongst
        his/her jobs, such as the name of the application program along
        with information from the document, such as the document name,
        document subject, or source file name.  If this attribute is not
        supplied by the client, the Printer generates a name to use in
        the "job-name" attribute of the newly created Job object (see
        Section 4.3.5).

     "ipp-attribute-fidelity" (boolean):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  The value 'true' indicates
        that total fidelity to client supplied Job Template attributes
        and values is required, else the Printer object MUST reject the
        Print-Job request.  The value 'false' indicates that a
        reasonable attempt to print the Job object is acceptable and the
        Printer object MUST accept the Print-job request. If not
        supplied, the Printer object assumes the value is 'false'.  All
        Printer objects MUST support both types of job processing.  See
        section 15 for a full description of "ipp-attribute-fidelity"
        and its relationship to other attributes, especially the Printer
        object's "pdl-override-supported" attribute.

     "document-name" (name(MAX)):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.   It contains the client
        supplied document name.  The document name MAY be different than
        the Job name.  Typically, the client software automatically
        supplies the document name on behalf of the end user by using a
        file name or an application generated name.  If this attribute
        is supplied, its value can be used in a manner defined by each
        implementation.  Examples include: printed along with the Job
        (job start sheet, page adornments, etc.), used by accounting or
        resource tracking management tools, or even stored along with
        the document as a document level attribute.  IPP/1.0 does not
        support the concept of document level attributes.

     "document-format" (mimeMediaType) :
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  The value of this attribute
        identifies the format of the supplied document data.  If the
        client does not supply this attribute, the Printer object
        assumes that the document data is in the format defined by the
        Printer object's "document-format-default" attribute.  If the
        client supplies this attribute, but the value is not supported
        by the Printer object, i.e., the value is not one of the values
        of the Printer object's "document-format-supported" attribute,
        the Printer object MUST reject the request and return the '
        client-error-document-format-not-supported' status code.

     "document-natural-language" (naturalLanguage):
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute. This attribute
        specifies the natural language of the document for those
        document-formats that require a specification of the natural
        language in order to image the document unambiguously. There are
        no particular values required for the Printer object to support.

     "compression" (type3 keyword)
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute and the "compression-
        supported" attribute (see section 4.4.29).  The client supplied
        "compression" operation attribute identifies the compression
        algorithm used on the document data.  If the client omits this
        attribute, the Printer object MUST assume that the data is not
        compressed.  If the client supplies the attribute and the
        Printer object supports the attribute, the Printer object uses
        the corresponding decompression algorithm on the document data.
        If the client supplies this attribute, but the value is not
        supported by the Printer object, i.e., the value is not one of
        the values of the Printer object's "compression-supported"
        attribute, the Printer object MUST copy the attribute and its
        value to the Unsupported Attributes response group, reject the
        request, and return the 'client-error-attributes-or-values-not-
        supported' status code.

     "job-k-octets" (integer(0:MAX))
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute and the "job-k-
        octets-supported" attribute (see section 4.4.30).  The client
        supplied "job-k-octets" operation attribute identifies the total
        size of the document(s) in K octets being submitted (see section
        4.3.17 for the complete semantics).  If the client supplies the

        attribute and the Printer object supports the attribute, the
        value of the attribute is used to populate the Job object's
        "job-k-octets" Job Description attribute.

        Note: For this attribute and the following two attributes
        ("job-impressions", and "job-media-sheets"), if the client
        supplies the attribute, but the Printer object does not support
        the attribute, the Printer object ignores the client-supplied
        value.  If the client supplies the attribute and the Printer
        supports the attribute, and the value is within the range of the
        corresponding Printer object's "xxx-supported" attribute, the
        Printer object MUST use the value to populate the Job object's
        "xxx" attribute.  If the client supplies the attribute and the
        Printer supports the attribute, but the value is outside the
        range of the corresponding Printer object's "xxx-supported"
        attribute, the Printer object MUST copy the attribute and its
        value to the Unsupported Attributes response group, reject the
        request, and return the 'client-error-attributes-or-values-not-
        supported' status code.  If the client does not supply the
        attribute, the Printer object MAY choose to populate the
        corresponding Job object attribute depending on whether the
        Printer object supports the attribute and is able to calculate
        or discern the correct value.

     "job-impressions" (integer(0:MAX))
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute and the "job-
        impressions-supported" attribute (see section 4.4.31).  The
        client supplied "job-impressions" operation attribute identifies
        the total size in number of impressions of the document(s) being
        submitted (see section 4.3.18 for the complete semantics).

        See note under "job-k-octets".

     "job-media-sheets" (integer(0:MAX))
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute and the "job-media-
        sheets-supported" attribute (see section 4.4.32).  The client
        supplied "job-media-sheets" operation attribute identifies the
        total number of media sheets to be produced for this job (see
        section 4.3.19 for the complete semantics).

        See note under "job-k-octets".

   Group 2: Job Template Attributes

        The client OPTIONALLY supplies a set of Job Template attributes
        as defined in section 4.2.  If the client is not supplying any
        Job Template attributes in the request, the client SHOULD omit
        Group 2 rather than sending an empty group.  However, a Printer
        object MUST be able to accept an empty group.

   Group 3: Document Content

        The client MUST supply the document data to be processed.

   Note: In addition to the MANDATORY parameters required for every
   operation request, the simplest Print-Job Request consists of just
   the "attributes-charset" and "attributes-natural-language" operation
   attributes; the "printer-uri" target operation attribute; the
   Document Content and nothing else.  In this simple case, the Printer
   object:

     - creates a new Job object (the Job object contains a single
       document),
     - stores a generated Job name in the "job-name" attribute in the
       natural language and charset requested (see Section 3.1.4.1) (if
       those are supported, otherwise using the Printer object's default
       natural language and charset), and
     - at job processing time, uses its corresponding default value
       attributes for the supported Job Template attributes that were
       not supplied by the client as IPP attribute or embedded
       instructions in the document data.

3.2.1.2 Print-Job Response

       The Printer object MUST return to the client the following sets
       of attributes as part of the Print-Job Response:

       Group 1: Operation Attributes

     Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text) operation attribute as described in sections 14 and
        3.1.6.  If the client supplies unsupported or conflicting Job
        Template attributes or values, the Printer object MUST reject or
        accept the Print-Job request depending on the whether the client
        supplied a 'true' or 'false' value for the "ipp-attribute-
        fidelity" operation attribute.  See the Implementer's Guide
        [ipp-iig] for a complete description of the suggested steps for
        processing a create request.

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

        This is a set of Operation and Job Template attributes supplied
        by the client (in the request) that are not supported by the
        Printer object or that conflict with one another (see the
        Implementer's Guide [ipp-iig]).  If the Printer object is not
        returning any Unsupported Attributes in the response, the
        Printer object SHOULD omit Group 2 rather than sending an empty
        group.  However, a client MUST be able to accept an empty group.

        Unsupported attributes fall into three categories:

        1. The Printer object does not support the supplied attribute
           (no matter what the attribute syntax or value).
        2. The Printer object does support the attribute, but does not
           support some or all of the particular attribute syntaxes or
           values supplied by the client (i.e., the Printer object does
           not have those attribute syntaxes or values in its
           corresponding "xxx-supported" attribute).
        3. The Printer object does support the attributes and values
           supplied, but the particular values are in conflict with one
           another, because they violate a constraint, such as not being
           able to staple transparencies.

        In the case of an unsupported attribute name, the Printer object
        returns the client-supplied attribute with a substituted "out-
        of-band" value of 'unsupported' indicating no support for the
        attribute itself (see the beginning of section 4.1).

        In the case of a supported attribute with one or more
        unsupported attribute syntaxes or values, the Printer object
        simply returns the client-supplied attribute with the
        unsupported attribute syntaxes or values as supplied by the
        client.  This indicates support for the attribute, but no
        support for that particular attribute syntax or value.  If the
        client supplies a multi-valued attribute with more than one
        value and the Printer object supports the attribute but only
        supports a subset of the client-supplied attribute syntaxes or
        values, the Printer object MUST return only those attribute
        syntaxes or values that are unsupported.

        In the case of two (or more) supported attribute values that are
        in conflict with one another (although each is supported
        independently, the values conflict when requested together

        within the same job), the Printer object MUST return all the
        values that it ignores or substitutes to resolve the conflict,
        but not any of the values that it is still using.  The choice
        for exactly how to resolve the conflict is implementation
        dependent.  See The Implementer's Guide [ipp-iig] for an
        example.

        In these three cases, the value of the "ipp-attribute-fidelity"
        supplied by the client does not affect what the Printer object
        returns.  The value of "ipp-attribute-fidelity" only affects
        whether the Print-Job operation is accepted or rejected.  If the
        job is accepted, the client may query the job using the Get-
        Job-Attributes operation requesting the unsupported attributes
        that were returned in the create response to see which
        attributes were ignored (not stored on the Job object) and which
        attributes were stored with other (substituted) values.

   Group 3: Job Object Attributes

     "job-uri" (uri):
        The Printer object MUST return the Job object's URI by returning
        the contents of the REQUIRED "job-uri" Job object attribute.
        The client uses the Job object's URI when directing operations
        at the Job object.  The Printer object always uses its
        configured security policy when creating the new URI.  However,
        if the Printer object supports more than one URI, the Printer
        object also uses information about which URI was used in the
        Print-Job Request to generated the new URI so that the new URI
        references the correct access channel.  In other words, if the
        Print-Job Request comes in over a secure channel, the Printer
        object MUST generate a Job URI that uses the secure channel as
        well.

     "job-id" (integer(1:MAX)):
        The Printer object MUST return the Job object's Job ID by
        returning the REQUIRED "job-id" Job object attribute.  The
        client uses this "job-id" attribute in conjunction with the
        "printer-uri" attribute used in the Print-Job Request when
        directing Job operations at the Printer object.

     "job-state":
        The Printer object MUST return the Job object's REQUIRED "job-
        state" attribute. The value of this attribute (along with the
        value of the next attribute "job-state-reasons") is taken from a
        "snapshot" of the new Job object at some meaningful point in
        time (implementation defined) between when the Printer object
        receives the Print-Job Request and when the Printer object
        returns the response.

     "job-state-reasons":
        The Printer object OPTIONALLY returns the Job object's OPTIONAL
        "job-state-reasons" attribute.  If the Printer object supports
        this attribute then it MUST be returned in the response.  If
        this attribute is not returned in the response, the client can
        assume that the "job-state-reasons" attribute is not supported
        and will not be returned in a subsequent Job object query.

     "job-state-message":
        The Printer object OPTIONALLY returns the Job object's OPTIONAL
        "job-state-message" attribute.  If the Printer object supports
        this attribute then it MUST be returned in the response.  If
        this attribute is not returned in the response, the client can
        assume that the "job-state-message" attribute is not supported
        and will not be returned in a subsequent Job object query.

     "number-of-intervening-jobs":
        The Printer object OPTIONALLY returns the Job object's OPTIONAL
        "number-of-intervening-jobs" attribute.  If the Printer object
        supports this attribute then it MUST be returned in the
        response.  If this attribute is not returned in the response,
        the client can assume that the "number-of-intervening-jobs"
        attribute is not supported and will not be returned in a
        subsequent Job object query.

        Note: Since any printer state information which affects a job's
        state is reflected in the "job-state" and "job-state-reasons"
        attributes, it is sufficient to return only these attributes and
        no specific printer status attributes.

   Note: In addition to the MANDATORY parameters required for every
   operation response, the simplest response consists of the just the
   "attributes-charset" and "attributes-natural-language" operation
   attributes and the "job-uri", "job-id", and "job-state" Job Object
   Attributes.  In this simplest case, the status code is "successful-
   ok" and there is no "status-message" operation attribute.

3.2.2 Print-URI Operation

   This OPTIONAL operation is identical to the Print-Job operation
   (section 3.2.1) except that a client supplies a URI reference to the
   document data using the "document-uri" (uri) operation attribute (in
   Group 1) rather than including the document data itself.  Before
   returning the response, the Printer MUST validate that the Printer
   supports the retrieval method (e.g., http, ftp, etc.) implied by the
   URI, and MUST check for valid URI syntax.  If the client-supplied URI
   scheme is not supported, i.e. the value is not in the Printer
   object's "referenced-uri-scheme-supported" attribute, the Printer

   object MUST reject the request and return the 'client-error-uri-
   scheme-not-supported' status code.  See The Implementer's Guide
   [ipp-iig] for suggested additional checks.  The Printer NEED NOT
   follow the reference and validate the contents of the reference.

   If the Printer object supports this operation, it MUST support the
   "reference-uri-schemes-supported" Printer attribute (see section
   4.4.24).

   It is up to the IPP object to interpret the URI and subsequently
   "pull" the document from the source referenced by the URI string.

3.2.3 Validate-Job Operation

   This REQUIRED operation is similar to the Print-Job operation
   (section 3.2.1) except that a client supplies no document data and
   the Printer allocates no resources (i.e., it does not create a new
   Job object).  This operation is used only to verify capabilities of a
   printer object against whatever attributes are supplied by the client
   in the Validate-Job request.  By using the Validate-Job operation a
   client can validate that an identical Print-Job operation (with the
   document data) would be accepted. The Validate-Job operation also
   performs the same security negotiation as the Print-Job operation
   (see section 8), so that a client can check that the client and
   Printer object security requirements can be met before performing a
   Print-Job operation.

   Note: The Validate-Job operation does not accept a "document-uri"
   attribute in order to allow a client to check that the same Print-URI
   operation will be accepted, since the client doesn't send the data
   with the Print-URI operation.  The client SHOULD just issue the
   Print-URI request.

   The Printer object returns the same status codes, Operation
   Attributes (Group 1) and Unsupported Attributes (Group 2) as the
   Print-Job operation.  However, no Job Object Attributes (Group 3) are
   returned, since no Job object is created.

3.2.4 Create-Job Operation

   This OPTIONAL operation is similar to the Print-Job operation
   (section 3.2.1) except that in the Create-Job request, a client does
   not supply document data or any reference to document data.  Also,
   the client does not supply any of the "document-name", "document-
   format", "compression", or "document-natural-language" operation
   attributes.  This operation is followed by one or more Send-Document
   or Send-URI operations.  In each of those operation requests, the

   client OPTIONALLY supplies the "document-name", "document-format",
   and "document-natural-language" attributes for each document in the
   multi-document Job object.

   If a Printer object supports the Create-Job operation, it MUST also
   support the Send-Document operation and also MAY support the Send-URI
   operation.

   If the Printer object supports this operation, it MUST support the
   "multiple-operation-time-out" Printer attribute (see section 4.4.28).

3.2.5 Get-Printer-Attributes Operation

   This REQUIRED operation allows a client to request the values of the
   attributes of a Printer object.   In the request, the client supplies
   the set of Printer attribute names and/or attribute group names in
   which the requester is interested.  In the response, the Printer
   object returns a corresponding attribute set with the appropriate
   attribute values filled in.

   For Printer objects, the possible names of attribute groups are:

     - 'job-template': all of the Job Template attributes that apply to
       a Printer object (the last two columns of the table in Section
       4.2).
     - 'printer-description': the attributes specified in Section 4.4.
     - 'all': the special group 'all' that includes all supported
       attributes.

   Since a client MAY request specific attributes or named groups, there
   is a potential that there is some overlap.  For example, if a client
   requests, 'printer-name' and 'all', the client is actually requesting
   the "printer-name" attribute twice: once by naming it explicitly, and
   once by inclusion in the 'all' group.  In such cases, the Printer
   object NEED NOT return each attribute only once in the response even
   if it is requested multiple times.  The client SHOULD NOT request the
   same attribute in multiple ways.

   It is NOT REQUIRED that a Printer object support all attributes
   belonging to a group (since some attributes are OPTIONAL).  However,
   it is REQUIRED that each Printer object support all group names.

3.2.5.1 Get-Printer-Attributes Request

   The following sets of attributes are part of the Get-Printer-
   Attributes Request:

   Group 1: Operation Attributes

     Natural Language and Character Set:
        attributes-charset" and "attributes-natural-language" butes as
        described in section 3.1.4.1.

     Target:
        The "printer-uri" (uri) operation attribute which is the target
        for this operation as described in section 3.1.5.

     Requesting User Name:
        The "requesting-user-name" (name(MAX)) attribute SHOULD be
        supplied by the client as described in section 8.3.

     "requested-attributes" (1setOf keyword) :
        The client OPTIONALLY supplies a set of attribute names and/or
        attribute group names in whose values the requester is
        interested.  The Printer object MUST support this attribute.  If
        the client omits this attribute, the Printer MUST respond as if
        this attribute had been supplied with a value of 'all'.

     "document-format" (mimeMediaType) :
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  This attribute is useful
        for a Printer object to determine the set of supported attribute
        values that relate to the requested document format.  The
        Printer object MUST return the attributes and values that it
        uses to validate a job on a create or Validate-Job operation in
        which this document format is supplied. The Printer object
        SHOULD return only (1) those attributes that are supported for
        the specified format and (2) the attribute values that are
        supported for the specified document format.  By specifying the
        document format, the client can get the Printer object to
        eliminate the attributes and values that are not supported for a
        specific document format.  For example, a Printer object might
        have multiple interpreters to support both '
        application/postscript' (for PostScript) and 'text/plain' (for
        text) documents.  However, for only one of those interpreters
        might the Printer object be able to support "number-up" with
        values of '1', '2', and '4'.  For the other interpreter it might
        be able to only support "number-up" with a value of '1'. Thus a

        client can use the Get-Printer-Attributes operation to obtain
        the attributes and values that will be used to accept/reject a
        create job operation.

        If the Printer object does not distinguish between different
        sets of supported values for each different document format when
        validating jobs in the create and Validate-Job operations, it
        MUST NOT distinguish between different document formats in the
        Get-Printer-Attributes operation. If the Printer object does
        distinguish between different sets of supported values for each
        different document format specified by the client, this
        specialization applies only to the following Printer object
        attributes:

       - Printer attributes that are Job Template attributes ("xxx-
          default" "xxx-supported", and "xxx-ready" in the Table in
          Section 4.2),
       - "pdl-override-supported",
       - "compression-supported",
       - "job-k-octets-supported",
       - "job-impressions-supported,
       - "job-media-sheets-supported"
       - "printer-driver-installer",
       - "color-supported", and
       - "reference-uri-schemes-supported"

        The values of all other Printer object attributes (including
        "document-format-supported") remain invariant with respect to
        the client supplied document format (except for new Printer
        description attribute as registered according to section 6.2).

        If the client omits this "document-format" operation attribute,
        the Printer object MUST respond as if the attribute had been
        supplied with the value of the Printer object's "document-
        format-default" attribute.  It is recommended that the client
        always supply a value for "document-format", since the Printer
        object's "document-format-default" may be 'application/octet-
        stream', in which case the returned attributes and values are
        for the union of the document formats that the Printer can
        automatically sense.  For more details, see the description of
        the 'mimeMediaType' attribute syntax in section 4.1.9.

        If the client supplies a value for the "document-format"
        Operation attribute that is not supported by the Printer, i.e.,
        is not among the values of the Printer object's "document-
        format-supported" attribute, the Printer object MUST reject the
        operation and return the 'client-error-document-format-not-
        supported' status code.

3.2.5.2 Get-Printer-Attributes Response

   The Printer object returns the following sets of attributes as part
   of the Get-Printer-Attributes Response:

   Group 1: Operation Attributes

     Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text) operation attribute as described in section 3.1.6.

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

        This is a set of Operation attributes supplied by the client (in
        the request) that are not supported by the Printer object or
        that conflict with one another (see sections 3.2.1.2 and 16).
        The response NEED NOT contain the "requested-attributes"
        operation attribute with any supplied values (attribute
        keywords) that were requested by the client but are not
        supported by the IPP object.  If the Printer object is not
        returning any Unsupported Attributes in the response, the
        Printer object SHOULD omit Group 2 rather than sending an empty
        group.  However, a client MUST be able to accept an empty group.

   Group 3: Printer Object Attributes

        This is the set of requested attributes and their current
        values.  The Printer object ignores (does not respond with) any
        requested attribute which is not supported.  The Printer object
        MAY respond with a subset of the supported attributes and
        values, depending on the security policy in force.  However, the
        Printer object MUST respond with the 'unknown' value for any
        supported attribute (including all REQUIRED attributes) for
        which the Printer object does not know the value.  Also the
        Printer object MUST respond with the 'no-value' for any
        supported attribute (including all REQUIRED attributes) for
        which the system administrator has not configured a value.  See
        the description of the "out-of-band" values in the beginning of
        Section 4.1.

3.2.6 Get-Jobs Operation

   This REQUIRED operation allows a client to retrieve the list of Job
   objects belonging to the target Printer object.  The client may also
   supply a list of Job attribute names and/or attribute group names.  A
   group of Job object attributes will be returned for each Job object
   that is returned.

   This operation is similar to the Get-Job-Attributes operation, except
   that this Get-Jobs operation returns attributes from possibly more
   than one object (see the description of Job attribute group names in
   section 3.3.4).

3.2.6.1 Get-Jobs Request

   The client submits the Get-Jobs request to a Printer object.

   The following groups of attributes are part of the Get-Jobs Request:

   Group 1: Operation Attributes

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.1.

     Target:
        The "printer-uri" (uri) operation attribute which is the target
        for this operation as described in section 3.1.5.

     Requesting User Name:
        The "requesting-user-name" (name(MAX)) attribute SHOULD be
        supplied by the client as described in section 8.3.

     "limit" (integer(1:MAX)):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute. It is an integer value that
        indicates a limit to the number of Job objects returned.  The
        limit is a "stateless limit" in that if the value supplied by
        the client is 'N', then only the first 'N' jobs are returned in
        the Get-Jobs Response.  There is no mechanism to allow for the
        next 'M' jobs after the first 'N' jobs.  If the client does not
        supply this attribute, the Printer object responds with all
        applicable jobs.

     "requested-attributes" (1setOf keyword):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  It is a set of Job
        attribute names and/or attribute groups names in whose values

        the requester is interested.  This set of attributes is returned
        for each Job object that is returned.  The allowed attribute
        group names are the same as those defined in the Get-Job-
        Attributes operation in section 3.3.4.  If the client does not
        supply this attribute, the Printer MUST respond as if the client
        had supplied this attribute with two values:  'job-uri' and '
        job-id'.

     "which-jobs" (type2 keyword):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  It indicates which Job
        objects MUST be returned by the Printer object. The values for
        this attribute are:

          'completed': This includes any Job object whose state is
             'completed', 'canceled', or 'aborted'.
          'not-completed': This includes any Job object whose state is '
             pending', 'processing', 'processing-stopped', or 'pending-
             held'.

        A Printer object MUST support both values.  However, if the
        mentation does not keep jobs in the 'completed', 'canceled', '
        aborted' states, then it returns no jobs when the 'completed'
        value is supplied.

        If a client supplies some other value, the Printer object MUST
        copy the attribute and the unsupported value to the Unsupported
        Attributes response group, reject the request, and return the '
        client-error-attributes-or-values-not-supported' status code.

        If the client does not supply this attribute, the Printer object
        MUST respond as if the client had supplied the attribute with a
        value of 'not-completed'.

     "my-jobs" (boolean):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  It indicates whether all
        jobs or just the jobs submitted by the requesting user of this
        request  MUST be returned by the Printer object.  If the client
        does not supply this attribute, the Printer object MUST respond
        as if the client had supplied the attribute with a value of '
        false', i.e., all jobs.  The means for authenticating the
        requesting user and matching the jobs is described in section 8.

3.2.6.2 Get-Jobs Response

   The Printer object returns all of the Job objects that match the
   criteria as defined by the attribute values supplied by the client in
   the request.  It is possible that no Job objects are returned since
   there may literally be no Job objects at the Printer, or there may be
   no Job objects that match the criteria supplied by the client.  If
   the client requests any Job attributes at all, there is a set of Job
   Object Attributes returned for each Job object.

   Group 1: Operation Attributes

     Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text) operation attribute as described in sections 14 and
        3.1.6.

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

        This is a set of Operation attributes supplied by the client (in
        the request) that are not supported by the Printer object or
        that conflict with one another (see sections 3.2.1.2 and the
        Implementer's Guide [ipp-iig]).  The response NEED NOT contain
        the "requested-attributes" operation attribute with any supplied
        values (attribute keywords) that were requested by the client
        but are not supported by the IPP object.  If the Printer object
        is not returning any Unsupported Attributes in the response, the
        Printer object SHOULD omit Group 2 rather than sending an empty
        group.  However, a client MUST be able to accept an empty group.

   Groups 3 to N: Job Object Attributes

        The Printer object responds with one set of Job Object
        Attributes for each returned Job object.  The Printer object
        ignores (does not respond with) any requested attribute or value
        which is not supported or which is restricted by the security
        policy in force, including whether the requesting user is the
        user that submitted the job (job originating user) or not (see
        section 8).  However, the Printer object MUST respond with the '
        unknown' value for any supported attribute (including all
        REQUIRED attributes) for which the Printer object does not know

        the value, unless it would violate the security policy.  See the
        description of the "out-of-band" values in the beginning of
        Section 4.1.

        Jobs are returned in the following order:

          - If the client requests all 'completed' Jobs (Jobs in the '
            completed', 'aborted', or 'canceled' states), then the Jobs
            are returned newest to oldest (with respect to actual
            completion time)
          - If the client requests all 'not-completed' Jobs (Jobs in the
            'pending', 'processing', 'pending-held', and 'processing-
            stopped' states), then Jobs are returned in relative
            chronological order of expected time to complete (based on
            whatever scheduling algorithm is configured for the Printer
            object).

3.3 Job Operations

   All Job operations are directed at Job objects.  A client MUST always
   supply some means of identifying the Job object in order to identify
   the correct target of the operation.  That job identification MAY
   either be a single Job URI or a combination of a Printer URI with a
   Job ID.  The IPP object implementation MUST support both forms of
   identification for every job.

3.3.1 Send-Document Operation

   This OPTIONAL operation allows a client to create a multi-document
   Job object that is initially "empty" (contains no documents).  In the
   Create-Job response, the Printer object returns the Job object's URI
   (the "job-uri" attribute) and the Job object's 32-bit identifier (the
   "job-id" attribute).  For each new document that the client desires
   to add, the client uses a Send-Document operation.  Each Send-
   Document Request contains the entire stream of document data for one
   document.

   Since the Create-Job and the send operations (Send-Document or Send-
   URI operations) that follow could occur over an arbitrarily long
   period of time for a particular job, a client MUST send another send
   operation within an IPP Printer defined minimum time interval after
   the receipt of the previous request for the job.  If a Printer object
   supports multiple document jobs, the Printer object MUST support the
   "multiple-operation-time-out" attribute (see section 4.4.28).  This
   attribute indicates the minimum number of seconds the Printer object
   will wait for the next send operation before taking some recovery
   action.

   An IPP object MUST recover from an errant client that does not supply
   a send operation, sometime after the minimum time interval specified
   by the Printer object's "multiple-operation-time-out" attribute.
   Such recovery MAY include any of the following or other recovery
   actions:

     1. Assume that the Job is an invalid job, start the process of
        changing the job state to 'aborted', add the 'aborted-by-system'
        value to the job's "job-state-reasons" attribute (see section
        4.3.8), if supported, and clean up all resources associated with
        the Job.  In this case, if another send operation is finally
        received, the Printer responds with an "client-error-not-
        possible" or "client-error-not-found" depending on whether or
        not the Job object is still around when the send operation
        finally arrives.
     2. Assume that the last send operation received was in fact the
        last document (as if the "last-document" flag had been set to '
        true'), close the Job object, and proceed to process it (i.e.,
        move the Job's state to 'pending').
     3. Assume that the last send operation received was in fact the
        last document, close the Job, but move it to the 'pending-held'
        and add the 'submission-interrupted' value to the job's "job-
        state-reasons" attribute (see section 4.3.8), if supported.
        This action allows the user or an operator to determine whether
        to continue processing the Job by moving it back to the '
        pending' state or to cancel the job.

   Each implementation is free to decide the "best" action to take
   depending on local policy, whether any documents have been added,
   whether the implementation spools jobs or not, and/or any other piece
   of information available to it.  If the choice is to abort the Job
   object, it is possible that the Job object may already have been
   processed to the point that some media sheet pages have been printed.

3.3.1.1 Send-Document Request

   The following attribute sets are part of the Send-Document Request:

   Group 1: Operation Attributes

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.1.

     Target:
        Either (1) the "printer-uri" (uri) plus "job-id"
        (integer(1:MAX))or (2) the "job-uri" (uri) operation
        attribute(s) which define the target for this operation as
        described in section 3.1.5.

     Requesting User Name:
        "requesting-user-name" (name(MAX)) attribute SHOULD be supplied
        by the client as described in section 8.3.

     "document-name" (name(MAX)):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  It contains the client
        supplied document name.  The document name MAY be different than
        the Job name.  It might be helpful, but NEED NOT be unique
        across multiple documents in the same Job.  Typically, the
        client software automatically supplies the document name on
        behalf of the end user by using a file name or an application
        generated name.  See the description of the "document-name"
        operation attribute in the Print-Job Request (section 3.2.1.1)
        for more information about this attribute

   "document-format" (mimeMediaType):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  The value of this attribute
        identifies the format of the supplied document data.  If the
        client does not supply this attribute, the Printer object
        assumes that the document data is in the format defined by the
        Printer object's "document-format-default" attribute.  If the
        client supplies this attribute, but the value is not supported
        by the Printer object, i.e., the value is not one of the values
        of the Printer object's "document-format-supported" attribute,
        the Printer object MUST reject the request and return the '
        client-error-document-format-not-supported' status code.

     "document-natural-language" (naturalLanguage):
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute.  This attribute
        specifies the natural language of the document for those
        document-formats that require a specification of the natural
        language in order to image the document unambiguously.  There
        are no particular values required for the Printer object to
        support.

     "compression" (type3 keyword)
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute and the "compression-
        supported" attribute (see section 4.4.29).  The client supplied

        "compression" operation attribute identifies the compression
        algorithm used on the document data.  If the client omits this
        attribute, the Printer object MUST assume that the data is not
        compressed.  If the client supplies the attribute and the
        Printer object supports the attribute, the Printer object MUST
        use the corresponding decompression algorithm on the document
        data. If the client supplies this attribute, but the value is
        not supported by the Printer object, i.e., the value is not one
        of the values of the Printer object's "compression-supported"
        attribute, the Printer object MUST copy the attribute and its
        value to the Unsupported Attributes response group, reject the
        request, and return the 'client-error-attributes-or-values-not-
        supported' status code.

     "last-document" (boolean):
        The client MUST supply this attribute.  The Printer object MUST
        support this attribute. It is a boolean flag that is set to '
        true' if this is the last document for the Job, 'false'
        otherwise.

   Group 2: Document Content

        The client MUST supply the document data if the "last-document"
        flag is set to 'false'.  However, since a client might not know
        that the previous document sent with a Send-Document (or Send-
        URI) operation was the last document (i.e., the "last-document"
        attribute was set to 'false'), it is legal to send a Send-
        Document request with no document data where the "last-document"
        flag is set to 'true'.  Such a request MUST NOT increment the
        value of the Job object's "number-of-documents" attribute, since
        no real document was added to the job.

3.3.1.2 Send-Document Response

   The following sets of attributes are part of the Send-Document
   Response:

   Group 1: Operation Attributes

     Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text) operation attribute as described in sections 14 and
        3.1.6.

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

        This is a set of Operation attributes supplied by the client (in
        the request) that are not supported by the Printer object or
        that conflict with one another (see sections 3.2.1.2 and the
        Implementer's Guide [ipp-iig]).  If the Printer object is not
        returning any Unsupported Attributes in the response, the
        Printer object SHOULD omit Group 2 rather than sending an empty
        group.  However, a client MUST be able to accept an empty group.

   Group 3: Job Object Attributes

        This is the same set of attributes as described in the Print-Job
        response (see section 3.2.1.2).

3.3.2 Send-URI Operation

   This OPTIONAL operation is identical to the Send-Document operation
   (see section 3.3.1) except that a client MUST supply a URI reference
   ("document-uri" operation attribute) rather than the document data
   itself.  If a Printer object supports this operation, clients can use
   both Send-URI or Send-Document operations to add new documents to an
   existing multi-document Job object.  However, if a client needs to
   indicate that the previous Send-URI or Send-Document was the last
   document,  the client MUST use the Send-Document operation with no
   document data and the "last-document" flag set to 'true' (rather than
   using a Send-URI operation with no "document-uri" operation
   attribute).

   If a Printer object supports this operation, it MUST also support the
   Print-URI operation (see section 3.2.2).

   The Printer object MUST validate the syntax and URI scheme of the
   supplied URI before returning a response, just as in the Print-URI
   operation.

3.3.3 Cancel-Job Operation

   This REQUIRED operation allows a client to cancel a Print Job from
   the time the job is created up to the time it is completed, canceled,
   or aborted.  Since a Job might already be printing by the time a
   Cancel-Job is received, some media sheet pages might be printed
   before the job is actually terminated.

3.3.3.1 Cancel-Job Request

   The following groups of attributes are part of the Cancel-Job
   Request:

   Group 1: Operation Attributes

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.1.

     Target:
        Either (1) the "printer-uri" (uri) plus "job-id"
        (integer(1:MAX))or (2) the "job-uri" (uri) operation
        attribute(s) which define the target for this operation as
        described in section 3.1.5.

     Requesting User Name:
        The "requesting-user-name" (name(MAX)) attribute SHOULD be
        supplied by the client as described in section 8.3.

     "message" (text(127)):
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute. It is a message to
        the operator.  This "message" attribute is not the same as the
        "job-message-from-operator" attribute.  That attribute is used
        to report a message from the operator to the end user that
        queries that attribute.  This "message" operation attribute is
        used to send a message from the client to the operator along
        with the operation request.  It is an implementation decision of
        how or where to display this message to the operator (if at
        all).

3.3.3.2 Cancel-Job Response

   The following sets of attributes are part of the Cancel-Job Response:

   Group 1: Operation Attributes

     Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text) operation attribute as described in sections 14 and
        3.1.6.

        If the job is already in the 'completed', 'aborted', or '
        canceled' state, or the 'process-to-stop-point' value is set in
        the Job's "job-state-reasons" attribute, the Printer object MUST
        reject the request and return the 'client-error-not-possible'
        error status code.

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

        This is a set of Operation attributes supplied by the client (in
        the request) that are not supported by the Printer object or
        that conflict with one another (see section 3.2.1.2 and the
        Implementer's Guide [ipp-iig]).  If the Printer object is not
        returning any Unsupported Attributes in the response, the
        Printer object SHOULD omit Group 2 rather than sending an empty
        group.  However, a client MUST be able to accept an empty group.

   Once a successful response has been sent, the implementation
   guarantees that the Job will eventually end up in the 'canceled'
   state. Between the time of the Cancel-Job operation is accepted and
   when the job enters the 'canceled' job-state (see section 4.3.7), the
   "job-state-reasons" attribute SHOULD contain the 'processing-to-
   stop-point' value which indicates to later queries that although the
   Job might still be 'processing', it will eventually end up in the '
   canceled' state, not the 'completed' state.

3.3.4 Get-Job-Attributes Operation

   This REQUIRED operation allows a client to request the values of
   attributes of a Job object and it is almost identical to the Get-
   Printer-Attributes operation (see section 3.2.5).  The only
   differences are that the operation is directed at a Job object rather
   than a Printer object, there is no "document-format" operation
   attribute used when querying a Job object, and the returned attribute
   group is a set of Job object attributes rather than a set of Printer
   object attributes.

   For Jobs, the possible names of attribute groups are:

     - 'job-template': all of the Job Template attributes that apply to a
       Job object (the first column of the table in Section 4.2).
     - 'job-description': all of the Job Description attributes specified
       in Section 4.3.
     - 'all': the special group 'all' that includes all supported
       attributes.

   Since a client MAY request specific attributes or named groups, there
   is a potential that there is some overlap.  For example, if a client
   requests, 'job-name' and 'job-description', the client is actually
   requesting the "job-name" attribute once by naming it explicitly, and
   once by inclusion in the 'job-description' group.  In such cases, the

   Printer object NEED NOT return the attribute only once in the
   response even if it is requested multiple times.  The client SHOULD
   NOT request the same attribute in multiple ways.

   It is NOT REQUIRED that a Job object support all attributes belonging
   to a group (since some attributes are OPTIONAL).  However it is
   REQUIRED that each Job object support all group names.

3.3.4.1 Get-Job-Attributes Request

   The following groups of attributes are part of the Get-Job-Attributes
   Request when the request is directed at a Job object:

   Group 1: Operation Attributes

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.1.

     Target:
        Either (1) the "printer-uri" (uri) plus "job-id"
        (integer(1:MAX)) or (2) the "job-uri" (uri) operation
        attribute(s) which define the target for this operation as
        described in section 3.1.5.

     Requesting User Name:
        The "requesting-user-name" (name(MAX)) attribute SHOULD be
        supplied by the client as described in section 8.3.

     "requested-attributes" (1setOf keyword) :
        The client OPTIONALLY supplies this attribute.  The IPP object
        MUST support this attribute.   It is a set of attribute names
        and/or attribute group names in whose values the requester is
        interested.  If the client omits this attribute, the IPP object
        MUST respond as if this attribute had been supplied with a value
        of 'all'.

3.3.4.2 Get-Job-Attributes Response

   The Printer object returns the following sets of attributes as part
   of the Get-Job-Attributes Response:

   Group 1: Operation Attributes

     Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text) operation attribute as described in sections 14 and
        3.1.6.

     Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.  The "attributes-
        natural-language" MAY be the natural language of the Job object,
        rather than the one requested.

   Group 2: Unsupported Attributes

        This is a set of Operation attributes supplied by the client (in
        the request) that are not supported by the Printer object or
        that conflict with one another (see sections 3.2.1.2 and the
        Implementer's Guide [ipp-iig]).  The response NEED NOT contain
        the "requested-attributes" operation attribute with any supplied
        values (attribute keywords) that were requested by the client
        but are not supported by the IPP object.  If the Printer object
        is not returning any Unsupported Attributes in the response, the
        Printer object SHOULD omit Group 2 rather than sending an empty
        group.  However, a client MUST be able to accept an empty group.

   Group 3: Job Object Attributes

        This is the set of requested attributes and their current
        values.  The IPP object ignores (does not respond with) any
        requested attribute or value which is not supported or which is
        restricted by the security policy in force, including whether
        the requesting user is the user that submitted the job (job
        originating user) or not (see section 8).  However, the IPP
        object MUST respond with the 'unknown' value for any supported
        attribute (including all RED butes) for which the IPP object
        does not know the value, s it would violate the security policy.
        See the description e "out-of-band" values in the beginning of
        Section 4.1.

4. Object Attributes

   This section describes the attributes with their corresponding
   attribute syntaxes and values that are part of the IPP model.  The
   sections below show the objects and their associated attributes which
   are included within the scope of this protocol.  Many of these
   attributes are derived from other relevant specifications:

     - Document Printing Application (DPA) [ISO10175]
     - RFC 1759 Printer MIB [RFC1759]

   Each attribute is uniquely identified in this document using a
   "keyword" (see section 12.2.1) which is the name of the attribute.
   The keyword is included in the section header describing that
   attribute.

   Note: Not only are keywords used to identify attributes, but one of
   the attribute syntaxes described below is "keyword" so that some
   attributes have keyword values.  Therefore, these attributes are
   defined as having an attribute syntax that is a set of keywords.

4.1 Attribute Syntaxes

   This section defines the basic attribute syntax types that all clients
   and IPP objects MUST be able to accept in responses and accept in
   requests, respectively.  Each attribute description in sections 3 and
   4 includes the name of attribute syntax(es) in the heading (in
   parentheses).  A conforming implementation of an attribute MUST
   include the semantics of the attribute syntax(es) so identified.
   Section 6.3 describes how the protocol can be extended with new
   attribute syntaxes.

   The attribute syntaxes are specified in the following sub-sections,
   where the sub-section heading is the keyword name of the attribute
   syntax inside the single quotes.  In operation requests and responses
   each attribute value MUST be represented as one of the attribute
   syntaxes specified in the sub-section heading for the attribute.  In
   addition, the value of an attribute in a response (but not in a
   request) MAY be one of the "out-of-band" values.  Standard
   "out-of-band" values are:

     'unknown': The attribute is supported by the IPP object, but the
        value is unknown to the IPP object for some reason.
     'unsupported': The attribute is unsupported by the IPP object.  This
        value MUST be returned only as the value of an attribute in the
        Unsupported Attributes Group.
     'no-value': The attribute is supported by the Printer object, but
        the system administrator has not yet configured a value.

   The Encoding and Transport specification [RFC2565] defines mechanisms
   for passing "out-of-band" values.  All attributes in a request MUST
   have one or more values as defined in Sections 4.2 to 4.4.  Thus
   clients MUST NOT supply attributes with "out-of-band" values.  All
   attribute in a response MUST have one or more values as defined in
   Sections 4.2 to 4.4 or a single "out-of-band" value.

   Most attributes are defined to have a single attribute syntax.
   However, a few attributes (e.g., "job-sheet", "media", "job-hold-
   until") are defined to have several attribute syntaxes, depending on
   the value.  These multiple attribute syntaxes are separated by the
   "|" character in the sub-section heading to indicate the choice.
   Since each value MUST be tagged as to its attribute syntax in the

   protocol, a single-valued attribute instance may have any one of its
   attribute syntaxes and a multi-valued attribute instance may have a
   mixture of its defined attribute syntaxes.

4.1.1 'text'

   A text attribute is an attribute whose value is a sequence of zero or
   more characters encoded in a maximum of 1023 ('MAX') octets.  MAX is
   the maximum length for each value of any text attribute.  However, if
   an attribute will always contain values whose maximum length is much
   less than MAX, the definition of that attribute will include a
   qualifier that defines the maximum length for values of that
   attribute.  For example: the "printer-location" attribute is
   specified as "printer-location (text(127))".  In this case, text
   values for "printer-location" MUST NOT exceed 127 octets; if supplied
   with a longer text string via some external interface (other than the
   protocol), implementations are free to truncate to this shorter
   length limitation.

   In this specification, all text attributes are defined using the '
   text' syntax.  However, 'text' is used only for brevity; the formal
   interpretation of 'text' is: 'textWithoutLanguage |
   textWithLanguage'.  That is, for any attribute defined in this
   specification using the 'text' attribute syntax, all IPP objects and
   clients MUST support both the 'textWithoutLanguage' and '
   textWithLanguage' attribute syntaxes.  However, in actual usage and
   protocol execution, objects and clients accept and return only one of
   the two syntax per attribute.  The syntax 'text' never appears "on-
   the-wire".

   Both 'textWithoutLanguage' and 'textWithLanguage' are needed to
   support the real world needs of interoperability between sites and
   systems that use different natural languages as the basis for human
   communication.  Generally, one natural language applies to all text
   attributes in a given request or response. The language is indicated
   by the "attributes-natural-language" operation attribute defined in
   section 3.1.4 or "attributes-natural-language" job attribute defined
   in section 4.3.24, and there is no need to identify the natural
   language for each text string on a value-by-value basis.  In these
   cases, the attribute syntax 'textWithoutLanguage' is used for text
   attributes.  In other cases, the client needs to supply or the

   Printer object needs to return a text value in a natural language
   that is different from the rest of the text values in the request or
   response.  In these cases, the client or Printer object uses the
   attribute syntax 'textWithLanguage' for text attributes (this is the
   Natural Language Override mechanism described in section 3.1.4).

   The 'textWithoutLanguage' and 'textWithLanguage' attribute syntaxes
   are described in more detail in the following sections.

4.1.1.1 'textWithoutLanguage'

   The 'textWithoutLanguage' syntax indicates a value that is sequence
   of zero or more characters.  Text strings are encoded using the rules
   of some charset.  The Printer object MUST support the UTF-8 charset
   [RFC2279] and MAY support additional charsets to represent 'text'
   values, provided that the charsets are registered with IANA [IANA-
   CS].  See Section 4.1.7 for the specification of the 'charset'
   attribute syntax, including restricted semantics and examples of
   charsets.

4.1.1.2 'textWithLanguage'

   The 'textWithLanguage' attribute syntax is a compound attribute
   syntax consisting of two parts: a 'textWithoutLanguage' part plus an
   additional 'naturalLanguage' (see section 4.1.8) part that overrides
   the natural language in force.  The 'naturalLanguage' part explicitly
   identifies the natural language that applies to the text part of that
   value and that value alone.  For any give text attribute, the '
   textWithoutLanguage' part is limited to the maximum length defined
   for that attribute, but the 'naturalLanguage' part is always limited
   to 63 octets. Using the 'textWithLanguage' attribute syntax rather
   than the normal 'textWithoutLanguage' syntax is the so-called Natural
   Language Override mechanism and MUST be supported by all IPP objects
   and clients.

   If the attribute is multi-valued (1setOf text), then the '
   textWithLanguage' attribute syntax MUST be used to explicitly specify
   each attribute value whose natural language needs to be overridden.
   Other values in a multi-valued 'text' attribute in a request or a
   response revert to the natural language of the operation attribute.

   In a create request, the Printer object MUST accept and store with
   the Job object any natural language in the "attributes-natural-
   language" operation attribute, whether the Printer object supports
   that natural language or not.  Furthermore, the Printer object MUST
   accept and store any 'textWithLanguage' attribute value, whether the

   Printer object supports that natural language or not.  These
   requirements are independent of the value of the "ipp-attribute-
   fidelity" operation attribute that the client MAY supply.

   Example: If the client supplies the "attributes-natural-language"
   operation attribute with the value: 'en' indicating English, but the
   value of the "job-name" attribute is in French, the client MUST use
   the 'textWithLanguage' attribute syntax with the following two
   values:

     'fr': Natural Language Override indicating French
     'Rapport Mensuel': the job name in French

   See the Encoding and Transport document [RFC2565] for a detailed
   example of the 'textWithLanguage' attribute syntax.

4.1.2 'name'

   This syntax type is used for user-friendly strings, such as a Printer
   name, that, for humans, are more meaningful than identifiers.  Names
   are never translated from one natural language to another.  The '
   name' attribute syntax is essentially the same as 'text', including
   the REQUIRED support of UTF-8 except that the sequence of characters
   is limited so that its encoded form MUST NOT exceed 255 (MAX) octets.

   Also like 'text', 'name' is really an abbreviated notation for either
   'nameWithoutLanguage' or 'nameWithLanguage'.  That is, all IPP
   objects and clients MUST support both the 'nameWithoutLanguage' and '
   nameWithLanguage' attribute syntaxes.  However, in actual usage and
   protocol execution, objects and clients accept and return only one of
   the two syntax per attribute.  The syntax 'name' never appears "on-
   the-wire".

   Note: Only the 'text' and 'name' attribute syntaxes permit the
   Natural Language Override mechanism.

   Some attributes are defined as 'type3 keyword | name'.  These
   attributes support values that are either type3 keywords or names.
   This dual-syntax mechanism enables a site administrator to extend
   these attributes to legally include values that are locally defined
   by the site administrator.  Such names are not registered with IANA.

4.1.2.1 'nameWithoutLanguage'

   The 'nameWithoutLanguage' syntax indicates a value that is sequence
   of zero or more characters so that its encoded form does not exceed
   MAX octets.

4.1.2.2 'nameWithLanguage'

   The 'nameWithLanguage' attribute syntax is a compound attribute
   syntax consisting of two parts: a 'nameWithoutLanguage' part plus an
   additional 'naturalLanguage' (see section 4.1.8) part that overrides
   the natural language in force.  The 'naturalLanguage' part explicitly
   identifies the natural language that applies to that name value and
   that name value alone.

   The 'nameWithLanguage' attribute syntax behaves the same as the '
   textWithLanguage' syntax.  If a name is in a language that is
   different than the rest of the object or operation, then this '
   nameWithLanguage' syntax is used rather than the generic '
   nameWithoutLanguage' syntax.

   Example: If the client supplies the "attributes-natural-language"
   operation attribute with the value: 'en' indicating English, but the
   "printer-name" attribute is in German, the client MUST use the '
   nameWithLanguage' attribute syntax as follows:

     'de':  Natural Language Override indicating German
     'Farbdrucker':  the Printer name in German

4.1.2.3 Matching 'name' attribute values

   For purposes of matching two 'name' attribute values for equality,
   such as in job validation (where a client-supplied value for
   attribute "xxx" is checked to see if the value is among the values of
   the Printer object's corresponding "xxx-supported" attribute), the
   following match rules apply:

        1. 'keyword' values never match 'name' values.

        2. 'name' (nameWithoutLanguage and nameWithLanguage) values
        match if (1) the name parts match and (2) the Associated
        Natural-Language parts (see section 3.1.4.1) match.  The
        matching rules are:

             a. the name parts match if the two names are identical
             character by character, except it is RECOMMENDED that case
             be ignored.  For example: 'Ajax-letter-head-white' MUST
             match 'Ajax-letter-head-white' and SHOULD match 'ajax-
             letter-head-white' and 'AJAX-LETTER-HEAD-WHITE'.

             b. the Associated Natural-Language parts match if the
             shorter of the two meets the syntactic requirements of RFC
             1766 [RFC1766] and matches byte for byte with the longer.
             For example, 'en' matches 'en', 'en-us' and 'en-gb', but

             matches neither 'fr' nor 'e'.

4.1.3 'keyword'

   The 'keyword' attribute syntax is a sequence of characters, length: 1
   to 255, containing only the US-ASCII [ASCII] encoded values for
   lowercase letters ("a" - "z"), digits ("0" - "9"), hyphen ("-"), dot
   ("."), and underscore ("_").  The first character MUST be a lowercase
   letter.  Furthermore, keywords MUST be in U.S. English.

   This syntax type is used for enumerating semantic identifiers of
   entities in the abstract protocol, i.e., entities identified in this
   document.  Keywords are used as attribute names or values of
   attributes.  Unlike 'text' and 'name' attribute values, 'keyword'
   values MUST NOT use the Natural Language Override mechanism, since
   they MUST always be US-ASCII and U.S. English.

   Keywords are for use in the protocol.  A user interface will likely
   provide a mapping between protocol keywords and displayable user-
   friendly words and phrases which are localized to the natural
   language of the user.  While the keywords specified in this document
   MAY be displayed to users whose natural language is U.S. English,
   they MAY be mapped to other U.S. English words for U.S. English
   users, since the user interface is outside the scope of this
   document.

   In the definition for each attribute of this syntax type, the full
   set of defined keyword values for that attribute are listed.

   When a keyword is used to represent an attribute (its name), it MUST
   be unique within the full scope of all IPP objects and attributes.
   When a keyword is used to represent a value of an attribute, it MUST
   be unique just within the scope of that attribute.  That is, the same
   keyword MUST NOT be used for two different values within the same
   attribute to mean two different semantic ideas.  However, the same
   keyword MAY be used across two or more attributes, representing
   different semantic ideas for each attribute.  Section 6.1 describes
   how the protocol can be extended with new keyword values.  Examples
   of attribute name keywords:

     "job-name"
     "attributes-charset"

   Note:  This document uses "type1", "type2", and "type3" prefixes to
   the "keyword" basic syntax to indicate different levels of review for
   extensions (see section 6.1).

4.1.4 'enum'

   The 'enum' attribute syntax is an enumerated integer value that is in
   the range from 1 to 2**31 - 1 (MAX).   Each value has an associated '
   keyword' name.  In the definition for each attribute of this syntax
   type, the full set of possible values for that attribute are listed.
   This syntax type is used for attributes for which there are enum
   values assigned by other standards, such as SNMP MIBs.  A number of
   attribute enum values in this specification are also used for
   corresponding attributes in other standards [RFC1759].  This syntax
   type is not used for attributes to which the system administrator may
   assign values.  Section 6.1 describes how the protocol can be
   extended with new enum values.

   Enum values are for use in the protocol.  A user interface will
   provide a mapping between protocol enum values and displayable user-
   friendly words and phrases which are localized to the natural
   language of the user.  While the enum symbols specified in this
   document MAY be displayed to users whose natural language is U.S.
   English, they MAY be mapped to other U.S. English words for U.S.
   English users, since the user interface is outside the scope of this
   document.

   Note: SNMP MIBs use '2' for 'unknown' which corresponds to the IPP
   "out-of-band" value 'unknown'.  See the description of the "out-of-
   band" values at the beginning of Section 4.1.  Therefore, attributes
   of type 'enum' start at '3'.

   Note:  This document uses "type1", "type2", and "type3" prefixes to
   the "enum" basic syntax to indicate different levels of review for
   extensions (see section 6.1).

4.1.5 'uri'

   The 'uri' attribute syntax is any valid Uniform Resource Identifier
   or URI [RFC2396].  Most often, URIs are simply Uniform Resource
   Locators or URLs.  The maximum length of URIs used as values of IPP
   attributes is 1023 octets.  Although most other IPP attribute syntax
   types allow for only lower-cased values, this attribute syntax type
   conforms to the case-sensitive and case-insensitive rules specified
   in [RFC2396].

4.1.6 'uriScheme'

   The 'uriScheme' attribute syntax is a sequence of characters
   representing a URI scheme according to RFC 2396 [RFC2396].  Though
   RFC 2396 requires that the values be case-insensitive, IPP requires

   all lower case values in IPP attributes to simplify comparing by IPP
   clients and Printer objects.  Standard values for this syntax type
   are the following keywords:

     'http':  for HTTP schemed URIs (e.g., "http:...")
     'https':  for use with HTTPS schemed URIs (e.g., "https:...")
        (not on IETF standards track)
     'ftp': for FTP schemed URIs (e.g., "ftp:...")
     'mailto': for SMTP schemed URIs (e.g., "mailto:...")
     'file': for file schemed URIs (e.g., "file:...")

   A Printer object MAY support any URI 'scheme' that has been
   registered with IANA [IANA-MT]. The maximum length of URI 'scheme'
   values used to represent IPP attribute values is 63 octets.

4.1.7 'charset'

   The 'charset' attribute syntax is a standard identifier for a
   charset.  A charset is a coded character set and encoding scheme.
   Charsets are used for labeling certain document contents and 'text'
   and 'name' attribute values.  The syntax and semantics of this
   attribute syntax are specified in RFC 2046 [RFC2046] and contained in
   the IANA character-set Registry [IANA-CS] according to the IANA
   procedures [RFC2278].  Though RFC 2046 requires that the values be
   case-insensitive US-ASCII, IPP requires all lower case values in IPP
   attributes to simplify comparing by IPP clients and Printer objects.
   When a character-set in the IANA registry has more than one name
   (alias), the name labeled as "(preferred MIME name)", if present,
   MUST be used.

   The maximum length of 'charset' values used to represent IPP
   attribute values is 63 octets.

   Some examples are:

     'utf-8':  ISO 10646 Universal Multiple-Octet Coded Character Set
        (UCS) represented as the UTF-8 [RFC2279] transfer encoding
        scheme in which US-ASCII is a subset charset.
     'us-ascii':  7-bit American Standard Code for Information
        Interchange (ASCII), ANSI X3.4-1986 [ASCII].  That standard
        defines US-ASCII, but RFC 2045 [RFC2045] eliminates most of the
        control characters from conformant usage in MIME and IPP.
     'iso-8859-1':  8-bit One-Byte Coded Character Set, Latin Alphabet
        Nr 1 [ISO8859-1].  That standard defines a coded character set
        that is used by Latin languages in the Western Hemisphere and
        Western Europe.  US-ASCII is a subset charset.

     'iso-10646-ucs-2':  ISO 10646 Universal Multiple-Octet Coded
        Character Set (UCS) represented as two octets (UCS-2), with the
        high order octet of each pair coming first (so-called Big Endian
        integer).

   Some attribute descriptions MAY place additional requirements on
   charset values that may be used, such as REQUIRED values that MUST be
   supported or additional restrictions, such as requiring that the
   charset have US-ASCII as a subset charset.

4.1.8 'naturalLanguage'

   The 'naturalLanguage' attribute syntax is a standard identifier for a
   natural language and optionally a country.  The values for this
   syntax type are defined by RFC 1766 [RFC1766].  Though RFC 1766
   requires that the values be case-insensitive US-ASCII, IPP requires
   all lower case to simplify comparing by IPP clients and Printer
   objects.  Examples include:

     'en':  for English
     'en-us': for US English
     'fr': for French
     'de':  for German

   The maximum length of 'naturalLanguage' values used to represent IPP
   attribute values is 63 octets.

4.1.9 'mimeMediaType'

   The 'mimeMediaType' attribute syntax is the Internet Media Type
   (sometimes called MIME type) as defined by RFC 2046 [RFC2046] and
   registered according to the procedures of RFC 2048 [RFC2048] for
   identifying a document format.  The value MAY include a charset
   parameter, depending on the specification of the Media Type in the
   IANA Registry [IANA-MT].  Although most other IPP syntax types allow
   for only lower-cased values, this syntax type allows for mixed-case
   values which are case-insensitive.

   Examples are:

     'text/html': An HTML document
     'text/plain': A plain text document in US-ASCII (RFC 2046 indicates
        that in the absence of the charset parameter MUST mean US-ASCII
        rather than simply unspecified) [RFC2046].
     'text/plain; charset=US-ASCII':  A plain text document in US-ASCII
        [52, 56].
     'text/plain; charset=ISO-8859-1':  A plain text document in ISO
        8859-1 (Latin 1) [ISO8859-1].

     'text/plain; charset=utf-8':  A plain text document in ISO 10646
        represented as UTF-8 [RFC2279]
     'text/plain, charset=iso-10646-ucs-2':  A plain text document in
        ISO 10646 represented in two octets (UCS-2) [ISO10646-1]
     'application/postscript':  A PostScript document [RFC2046]
     'application/vnd.hp-PCL':  A PCL document [IANA-MT] (charset escape
        sequence embedded in the document data)
     'application/octet-stream':  Auto-sense - see below

   One special type is 'application/octet-stream'.  If the Printer
   object supports this value, the Printer object MUST be capable of
   auto-sensing the format of the document data.  If the Printer
   object's default value attribute "document-format-default" is set to
   'application/octet-stream', the Printer object not only supports
   auto-sensing of the document format, but will depend on the result of
   applying its auto-sensing when the client does not supply the
   "document-format" attribute.  If the client supplies a document
   format value, the Printer MUST rely on the supplied attribute, rather
   than trust its auto-sensing algorithm.  To summarize:

     1. If the client does not supply a document format value, the
        Printer MUST rely on its default value setting (which may be '
        application/octet-stream' indicating an auto-sensing mechanism).
     2. If the client supplies a value other than 'application/octet-
        stream', the client is supplying valid information about the
        format of the document data and the Printer object MUST trust
        the client supplied value more than the outcome of applying an
        automatic format detection mechanism.  For example, the client
        may be requesting the printing of a PostScript file as a '
        text/plain' document.  The Printer object MUST print a text
        representation of the PostScript commands rather than interpret
        the stream of PostScript commands and print the result.
     3. If the client supplies a value of 'application/octet-stream',
        the client is indicating that the Printer object MUST use its
        auto-sensing mechanism on the client supplied document data
        whether auto-sensing is the Printer object's default or not.

   Note:  Since the auto-sensing algorithm is probabilistic, if the
   client requests both auto-sensing ("document-format" set to '
   application/octet-stream') and true fidelity ("ipp-attribute-
   fidelity" set to 'true'), the Printer object might not be able to
   guarantee exactly what the end user intended (the auto-sensing
   algorithm might mistake one document format for another ), but it is
   able to guarantee that its auto-sensing mechanism be used.

   The maximum length of a 'mimeMediaType' value to represent IPP
   attribute values is 255 octets.

4.1.10 'octetString'

   The 'octetString' attribute syntax is a sequence of octets encoded in
   a maximum of 1023 octets which is indicated in sub-section headers
   using the notation: octetString(MAX).  This syntax type is used for
   opaque data.

4.1.11 'boolean'

   The 'boolean' attribute syntax has only two values:  'true' and '
   false'.

4.1.12 'integer'

   The 'integer' attribute syntax is an integer value that is in the
   range from -2**31 (MIN) to 2**31 - 1 (MAX).  Each individual
   attribute may specify the range constraint explicitly in sub-section
   headers if the range is different from the full range of possible
   integer values.  For example:  job-priority (integer(1:100)) for the
   "job-priority" attribute.  However, the enforcement of that
   additional constraint is up to the IPP objects, not the protocol.

4.1.13 'rangeOfInteger'

   The 'rangeOfInteger' attribute syntax is an ordered pair of integers
   that defines an inclusive range of integer values.  The first integer
   specifies the lower bound and the second specifies the upper bound.
   If a range constraint is specified in the header description for an
   attribute in this document whose attribute syntax is 'rangeOfInteger'
   (i.e., 'X:Y' indicating X as a minimum value and Y as a maximum
   value), then the constraint applies to both integers.

4.1.14 'dateTime'

   The 'dateTime' attribute syntax is a standard, fixed length, 11 octet
   representation of the "DateAndTime" syntax as defined in RFC 2579
   [RFC2579].  RFC 2579 also identifies an 8 octet representation of a
   "DateAndTime" value, but IPP objects MUST use the 11 octet
   representation.  A user interface will provide a mapping between
   protocol dateTime values and displayable user-friendly words or
   presentation values and phrases  which are localized to the natural
   language and date format of the user.

4.1.15 'resolution'

   The 'resolution' attribute syntax specifies a two-dimensional
   resolution in the indicated units.  It consists of 3 values: a cross
   feed direction resolution (positive integer value), a feed direction

   resolution (positive integer value), and a units value.  The
   semantics of these three components are taken from the Printer MIB
   [RFC1759] suggested values.  That is, the cross feed direction
   component resolution component is the same as the
   prtMarkerAddressabilityXFeedDir object in the Printer MIB, the feed
   direction component resolution component is the same as the
   prtMarkerAddressabilityFeedDir in the Printer MIB, and the units
   component is the same as the prtMarkerAddressabilityUnit object in
   the Printer MIB (namely, '3' indicates dots per inch and '4'
   indicates dots per centimeter).  All three values MUST be present
   even if the first two values are the same.  Example:  '300', '600', '
   3' indicates a 300 dpi cross-feed direction resolution, a 600 dpi
   feed direction resolution, since a '3' indicates dots per inch (dpi).

4.1.16 '1setOf  X'

   The '1setOf  X' attribute syntax is 1 or more values of attribute
   syntax type X.  This syntax type is used for multi-valued attributes.
   The syntax type is called '1setOf' rather than just 'setOf' as a
   reminder that the set of values MUST NOT be empty (i.e., a set of
   size 0).  Sets are normally unordered.  However each attribute
   description of this type may specify that the values MUST be in a
   certain order for that attribute.

4.2 Job Template Attributes

   Job Template attributes describe job processing behavior.  Support
   for Job Template attributes by a Printer object is OPTIONAL (see
   section 13.2.3 for a description of support for OPTIONAL attributes).
   Also, clients OPTIONALLY supply Job Template attributes in create
   requests.

   Job Template attributes conform to the following rules.  For each Job
   Template attribute called "xxx":

     1. If the Printer object supports "xxx" then it MUST support both a
        "xxx-default" attribute (unless there is a "No" in the table
        below) and a "xxx-supported" attribute.  If the Printer object
        doesn't support "xxx", then it MUST support neither an "xxx-
        default" attribute nor an "xxx-supported" attribute, and it MUST
        treat an attribute "xxx" supplied by a client as unsupported.
        An attribute "xxx" may be supported for some document formats
        and not supported for other document formats.  For example, it
        is expected that a Printer object would only support
        "orientation-requested" for some document formats (such as '
        text/plain' or 'text/html') but not others (such as '
        application/postscript').

     2. "xxx" is OPTIONALLY supplied by the client in a create request.
        If "xxx" is supplied, the client is indicating a desired job
        processing behavior for this Job.  When "xxx" is not supplied,
        the client is indicating that the Printer object apply its
        default job processing behavior at job processing time if the
        document content does not contain an embedded instruction
        indicating an xxx-related behavior.

        Note: Since an administrator MAY change the default value
        attribute after a Job object has been submitted but before it
        has been processed, the default value used by the Printer object
        at job processing time may be different that the default value
        in effect at job submission time.

     3. The "xxx-supported" attribute is a Printer object attribute that
        describes which job processing behaviors are supported by that
        Printer object.  A client can query the Printer object to find
        out what xxx-related behaviors are supported by inspecting the
        returned values of the "xxx-supported" attribute.

        Note: The "xxx" in each "xxx-supported" attribute name is
        singular, even though an "xxx-supported" attribute usually has
        more than one value, such as "job-sheet-supported", unless the
        "xxx" Job Template attribute is plural, such as "finishings" or
        "sides".  In such cases the "xxx-supported" attribute names are:
        "finishings-supported" and "sides-supported".

     4. The "xxx-default" default value attribute describes what will be
        done at job processing time when no other job processing
        information is supplied by the client (either explicitly as an
        IPP attribute in the create request or implicitly as an embedded
        instruction within the document data).

   If an application wishes to present an end user with a list of
   supported values from which to choose, the application SHOULD query
   the Printer object for its supported value attributes.  The
   application SHOULD also query the default value attributes.  If the
   application then limits selectable values to only those value that
   are supported, the application can guarantee that the values supplied
   by the client in the create request all fall within the set of
   supported values at the Printer.  When querying the Printer, the
   client MAY enumerate each attribute by name in the Get-Printer-
   Attributes Request, or the client MAY just name the "job-template"
   group in order to get the complete set of supported attributes (both
   supported and default attributes).

   The "finishings" attribute is an example of a Job Template attribute.
   It can take on a set of values such as 'staple', 'punch', and/or '
   cover'.  A client can query the Printer object for the "finishings-
   supported" attribute and the "finishings-default" attribute.  The
   supported attribute contains a set of supported values.  The default
   value attribute contains the finishing value(s) that will be used for
   a new Job if the client does not supply a "finishings" attribute in
   the create request and the document data does not contain any
   corresponding finishing instructions.  If the client does supply the
   "finishings" attribute in the create request, the IPP object
   validates the value or values to make sure that they are a subset of
   the supported values identified in the Printer object's "finishings-
   supported" attribute.  See section 3.2.1.2.

   The table below summarizes the names and relationships for all Job
   Template attributes. The first column of the table (labeled "Job
   Attribute") shows the name and syntax for each Job Template attribute
   in the Job object. These are the attributes that can optionally be
   supplied by the client in a create request.   The last two columns
   (labeled "Printer: Default Value Attribute" and "Printer: Supported
   Values Attribute") shows the name and syntax for each Job Template
   attribute in the Printer object (the default value attribute and the
   supported values attribute).  A "No" in the table means the Printer
   MUST NOT support the attribute (that is, the attribute is simply not
   applicable).  For brevity in the table, the 'text' and 'name' entries
   do not show the maximum length for each attribute.

     +===================+======================+======================+
     | Job Attribute     |Printer: Default Value|  Printer: Supported  |
     |                   |   Attribute          |   Values Attribute   |
     +===================+======================+======================+
     | job-priority      | job-priority-default |job-priority-supported|
     | (integer 1:100)   | (integer 1:100)      |(integer 1:100)       |
     +-------------------+----------------------+----------------------+
     | job-hold-until    | job-hold-until-      |job-hold-until-       |
     | (type3 keyword |  |  default             | supported            |
     |    name)          |  (type3 keyword |    |(1setOf               |
     |                   |    name)             | type3 keyword | name)|
     +-------------------+----------------------+----------------------+
     | job-sheets        | job-sheets-default   |job-sheets-supported  |
     | (type3 keyword |  | (type3 keyword |     |(1setOf               |
     |    name)          |    name)             | type3 keyword | name)|
     +-------------------+----------------------+----------------------+
     |multiple-document- |multiple-document-    |multiple-document-    |
     | handling          | handling-default     |handling-supported    |
     | (type2 keyword)   | (type2 keyword)      |(1setOf type2 keyword)|
     +-------------------+----------------------+----------------------+

     +===================+======================+======================+
     | Job Attribute     |Printer: Default Value|  Printer: Supported  |
     |                   |   Attribute          |   Values Attribute   |
     +===================+======================+======================+
     | copies            | copies-default       | copies-supported     |
     | (integer (1:MAX)) | (integer (1:MAX))    | (rangeOfInteger      |
     |                   |                      |       (1:MAX))       |
     +-------------------+----------------------+----------------------+
     | finishings        | finishings-default   | finishings-supported |
     |(1setOf type2 enum)|(1setOf type2 enum)   |(1setOf type2 enum)   |
     +-------------------+----------------------+----------------------+
     | page-ranges       | No                   | page-ranges-         |
     | (1setOf           |                      | supported (boolean)  |
     |   rangeOfInteger  |                      |                      |
     |        (1:MAX))   |                      |                      |
     +-------------------+----------------------+----------------------+
     | sides             | sides-default        | sides-supported      |
     | (type2 keyword)   | (type2 keyword)      |(1setOf type2 keyword)|
     +-------------------+----------------------+----------------------+
     | number-up         | number-up-default    | number-up-supported  |
     | (integer (1:MAX)) | (integer (1:MAX))    |(1setOf integer       |
     |                   |                      | (1:MAX) |            |
     |                   |                      |  rangeOfInteger      |
     |                   |                      |   (1:MAX))           |
     +-------------------+----------------------+----------------------+
     | orientation-      |orientation-requested-|orientation-requested-|
     |  requested        |  default             |  supported           |
     |   (type2 enum)    |  (type2 enum)        |  (1setOf type2 enum) |
     +-------------------+----------------------+----------------------+
     | media             | media-default        | media-supported      |
     | (type3 keyword |  | (type3 keyword |     |(1setOf               |
     |    name)          |    name)             | type3 keyword | name)|
     |                   |                      |                      |
     |                   |                      | media-ready          |
     |                   |                      |(1setOf               |
     |                   |                      | type3 keyword | name)|
     +-------------------+----------------------+----------------------+
     | printer-resolution| printer-resolution-  | printer-resolution-  |
     | (resolution)      |  default             | supported            |
     |                   | (resolution)         |(1setOf resolution)   |
     +-------------------+----------------------+----------------------+
     | print-quality     | print-quality-default| print-quality-       |
     | (type2 enum)      | (type2 enum)         | supported            |
     |                   |                      |(1setOf type2 enum)   |
     +-------------------+----------------------+----------------------+

4.2.1 job-priority (integer(1:100))

   This attribute specifies a priority for scheduling the Job. A higher
   value specifies a higher priority. The value 1 indicates the lowest
   possible priority. The value 100 indicates the highest possible
   priority.  Among those jobs that are ready to print, a Printer MUST
   print all jobs with a priority value of n before printing those with
   a priority value of n-1 for all n.

   If the Printer object supports this attribute, it MUST always support
   the full range from 1 to 100.  No administrative restrictions are
   permitted.  This way an end-user can always make full use of the
   entire range with any Printer object.  If privileged jobs are
   implemented outside IPP/1.0, they MUST have priorities higher than
   100, rather than restricting the range available to end-users.

   If the client does not supply this attribute and this attribute is
   supported by the Printer object, the Printer object MUST use the
   value of the Printer object's "job-priority-default" at job
   submission time (unlike most Job Template attributes that are used if
   necessary at job processing time).

   The syntax for the "job-priority-supported" is also integer(1:100).
   This single integer value indicates the number of priority levels
   supported.  The Printer object MUST take the value supplied by the
   client and map it to the closest integer in a sequence of n integers
   values that are evenly distributed over the range from 1 to 100 using
   the formula:

        roundToNearestInt((100x+50)/n)

   where n is the value of "job-priority-supported" and x ranges from 0
   through n-1.

   For example, if n=1 the sequence of values is 50;  if n=2, the
   sequence of values is:  25 and 75;  if n = 3, the sequence of values
   is:  17, 50 and 83;  if n = 10, the sequence of values is: 5, 15, 25,
   35, 45, 55, 65, 75, 85, and 95;  if n = 100, the sequence of values
   is:  1, 2, 3, .  100.

   If the value of the Printer object's "job-priority-supported" is 10
   and the client supplies values in the range 1 to 10, the Printer
   object maps them to 5, in the range 11 to 20, the Printer object maps
   them to 15, etc.

4.2.2 job-hold-until (type3 keyword | name (MAX))

   This attribute specifies the named time period during which the Job
   MUST become a candidate for printing.

   Standard keyword values for named time periods are:

     'no-hold': immediately, if there are not other reasons to hold the
        job
     'day-time': during the day
     'evening': evening
     'night': night
     'weekend': weekend
     'second-shift': second-shift (after close of business)
     'third-shift': third-shift (after midnight)

   An administrator MUST associate allowable print times with a named
   time period (by means outside IPP/1.0).  An administrator is
   encouraged to pick names that suggest the type of time period. An
   administrator MAY define additional values using the 'name' or '
   keyword' attribute syntax, depending on implementation.

   If the value of this attribute specifies a time period that is in the
   future, the Printer MUST add the 'job-hold-until-specified' value to
   the job's "job-state-reasons" attribute, move the job to the '
   pending-held' state, and MUST NOT schedule the job for printing until
   the specified time-period arrives.  When the specified time period
   arrives, the Printer MUST remove the 'job-hold-until-specified' value
   from the job's "job-state-reason" attribute and, if there are no
   other job state reasons that keep the job in the 'pending-held'
   state, the Printer MUST consider the job as a candidate for
   processing by moving the job to the 'pending' state.

   If this job attribute value is the named value 'no-hold', or the
   specified time period has already started, the job MUST be a
   candidate for processing immediately.

   If the client does not supply this attribute and this attribute is
   supported by the Printer object, the Printer object MUST use the
   value of the Printer object's "job-hold-until-default" at job
   submission time (unlike most Job Template attributes that are used if
   necessary at job processing time).

4.2.3 job-sheets (type3 keyword | name(MAX))

   This attribute determines which job start/end sheet(s), if any, MUST
   be printed with a job.

   Standard keyword values are:

     'none': no job sheet is printed
     'standard': one or more site specific standard job sheets are
        printed, e.g. a single start sheet or both start and end sheet
        is printed

   An administrator MAY define additional values using the 'name' or '
   keyword' attribute syntax, depending on implementation.

   Note: The effect of this attribute on jobs with multiple documents
   MAY be affected by the "multiple-document-handling" job attribute
   (section 4.2.4), depending on the job sheet semantics.

4.2.4 multiple-document-handling (type2 keyword)

   This attribute is relevant only if a job consists of two or more
   documents. The attribute controls finishing operations and the
   placement of one or more print-stream pages into impressions and onto
   media sheets.  When the value of the "copies" attribute exceeds 1, it
   also controls the order in which the copies that result from
   processing the documents are produced. For the purposes of this
   explanations, if "a" represents an instance of document data, then
   the result of processing the data in document "a" is a sequence of
   media sheets represented by "a(*)".

   Standard keyword values are:

     'single-document': If a Job object has multiple documents, say, the
        document data is called a and b, then the result of processing
        all the document data (a and then b) MUST be treated as a single
        sequence of media sheets for finishing operations; that is,
        finishing would be performed on the concatenation of the
        sequences a(*),b(*).  The Printer object MUST NOT force the data
        in each document instance to be formatted onto a new print-
        stream page, nor to start a new impression on a new media sheet.
        If more than one copy is made, the ordering of the sets of media
        sheets resulting from processing the document data MUST be a(*),
        b(*), a(*), b(*), ..., and the Printer object MUST force each
        copy (a(*),b(*)) to start on a new media sheet.
     'separate-documents-uncollated-copies': If a Job object has
        multiple documents, say, the document data is called a and b,
        then the result of processing the data in each document instance
        MUST be treated as a single sequence of media sheets for
        finishing operations; that is, the sets a(*) and b(*) would each
        be finished separately. The Printer object MUST force each copy
        of the result of processing the data in a single document to
        start on a new media sheet. If more than one copy is made, the

        ordering of the sets of media sheets resulting from processing
        the document data MUST be a(*), a(*), ..., b(*), b(*) ... .
     'separate-documents-collated-copies': If a Job object has multiple
        documents, say, the document data is called a and b, then the
        result of processing the data in each document instance MUST be
        treated as a single sequence of media sheets for finishing
        operations; that is, the sets a(*) and b(*) would each be
        finished separately. The Printer object MUST force each copy of
        the result of processing the data in a single document to start
        on a new media sheet.  If more than one copy is made, the
        ordering of the sets of media sheets resulting from processing
        the document data MUST be a(*), b(*), a(*), b(*), ... .
     'single-document-new-sheet':  Same as 'single-document', except
        that the Printer object MUST ensure that the first impression of
        each document instance in the job is placed on a new media
        sheet.  This value allows multiple documents to be stapled
        together with a single staple where each document starts on a
        new sheet.

   The 'single-document' value is the same as 'separate-documents-
   collated-copies' with respect to ordering of print-stream pages, but
   not media sheet generation, since 'single-document' will put the
   first page of the next document on the back side of a sheet if an odd
   number of pages have been produced so far for the job, while '
   separate-documents-collated-copies' always forces the next document
   or document copy on to a new sheet.  In addition, if the "finishings"
   attribute specifies 'staple', then with 'single-document', documents
   a and b are stapled together as a single document with no regard to
   new sheets, with 'single-document-new-sheet', documents a and b are
   stapled together as a single document, but document b starts on a new
   sheet, but with 'separate-documents-uncollated-copies' and '
   separate-documents-collated-copies', documents a and b are stapled
   separately.

   Note: None of these values provide means to produce uncollated sheets
   within a document, i.e., where multiple copies of sheet n are
   produced before sheet n+1 of the same document.

   The relationship of this attribute and the other attributes that
   control document processing is described in section 15.3.

4.2.5 copies (integer(1:MAX))

   This attribute specifies the number of copies to be printed.

   On many devices the supported number of collated copies will be
   limited by the number of physical output bins on the device, and may
   be different from the number of uncollated copies which can be

   supported.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.6 finishings (1setOf type2 enum)

   This attribute identifies the finishing operations that the Printer
   uses for each copy of each printed document in the Job. For Jobs with
   multiple documents, the "multiple-document-handling" attribute
   determines what constitutes a "copy" for purposes of finishing.

   Standard enum values are:

     Value  Symbolic Name and Description

     '3'    'none':  Perform no finishing
     '4'    'staple':  Bind the document(s) with one or more staples.
                  The exact number and placement of the staples is
                  site-defined.
     '5'    'punch':  This value indicates that holes are required in
                  the finished document. The exact number and placement
                  of the holes is site-defined  The punch specification
                  MAY be satisfied (in a site- and implementation-
                  specific manner) either by drilling/punching, or by
                  substituting pre-drilled media.
     '6'    'cover':  This value is specified when it is desired to
                  select a non-printed (or pre-printed) cover for the
                  document.  This does not supplant the specification of
                  a printed cover (on cover stock medium) by the
                  document itself.
     '7'    'bind':  This value indicates that a binding is to be
                  applied to the document; the type and placement of the
                  binding is site-defined."

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

   If the client supplies a value of 'none' along with any other
   combination of values, it is the same as if only that other
   combination of values had been supplied (that is the 'none' value has
   no effect).

4.2.7 page-ranges (1setOf rangeOfInteger (1:MAX))

   This attribute identifies the range(s) of print-stream pages that the
   Printer object uses for each copy of each document which are to be
   printed.  Nothing is printed for any pages identified that do not
   exist in the document(s).  Ranges MUST be in ascending order, for
   example: 1-3, 5-7, 15-19 and MUST NOT overlap, so that a non-spooling
   Printer object can process the job in a single pass.  If the ranges
   are not ascending or are overlapping, the IPP object MUST reject the
   request and return the 'client-error-bad-request' status code.  The
   attribute is associated with print-stream pages not application-
   numbered pages (for example, the page numbers found in the headers
   and or footers for certain word processing applications).

   For Jobs with multiple documents, the "multiple-document-handling"
   attribute determines what constitutes a "copy" for purposes of the
   specified page range(s).  When "multiple-document-handling" is '
   single-document', the Printer object MUST apply each supplied page
   range once to the concatenation of the print-stream pages.  For
   example, if there are 8 documents of 10 pages each, the page-range '
   41:60' prints the pages in the 5th and 6th documents as a single
   document and none of the pages of the other documents are printed.
   When "multiple-document-handling" is 'separate-documents-uncollated-
   copies' or 'separate-documents-collated-copies', the Printer object
   MUST apply each supplied page range repeatedly to each document copy.
   For the same job, the page-range '1:3, 10:10' would print the first 3
   pages and the 10th page of each of the 8 documents in the Job, as 8
   separate documents.

   In most cases, the exact pages to be printed will be generated by a
   device driver and this attribute would not be required.  However,
   when printing an archived document which has already been formatted,
   the end user may elect to print just a subset of the pages contained
   in the document.  In this case, if page-range = n.m is specified, the
   first page to be printed will be page n. All subsequent pages of the
   document will be printed through and including page m.

   "page-ranges-supported" is a boolean value indicating whether or not
   the printer is capable of supporting the printing of page ranges.
   This capability may differ from one PDL to another. There is no
   "page-ranges-default" attribute.  If the "page-ranges" attribute is
   not supplied by the client, all pages of the document will be
   printed.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.8 sides (type2 keyword)

   This attribute specifies how print-stream pages are to be imposed
   upon the sides of an instance of a selected medium, i.e., an
   impression.

   The standard keyword values are:

     'one-sided': imposes each consecutive print-stream page upon the
        same side of consecutive media sheets.
     'two-sided-long-edge': imposes each consecutive pair of print-
        stream pages upon front and back sides of consecutive media
        sheets, such that the orientation of each pair of print-stream
        pages on the medium would be correct for the reader as if for
        binding on the long edge.  This imposition is sometimes called '
        duplex' or 'head-to-head'.
     'two-sided-short-edge': imposes each consecutive pair of print-
        stream pages upon front and back sides of consecutive media
        sheets, such that the orientation of each pair of print-stream
        pages on the medium would be correct for the reader as if for
        binding on the short edge.  This imposition is sometimes called
        'tumble' or 'head-to-toe'.

   'two-sided-long-edge', 'two-sided-short-edge', 'tumble', and 'duplex'
   all work the same for portrait or landscape.  However 'head-to-toe'
   is 'tumble' in portrait but 'duplex' in landscape.  'head-to-head'
   also switches between 'duplex' and 'tumble' when using portrait and
   landscape modes.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.9 number-up (integer(1:MAX))

   This attribute specifies the number of print-stream pages to impose
   upon a single side of an instance of a selected medium.  For example,
   if the value is:

     Value  Description

     '1'    the Printer MUST place one print-stream page on a single
                  side of an instance of the selected medium (MAY add
                  some sort of translation, scaling, or rotation).
     '2'    the Printer MUST place two print-stream pages on a single
                  side of an instance of the selected medium (MAY add
                  some sort of translation, scaling, or rotation).
     '4'    the Printer MUST place four print-stream pages on a single
                  side of an instance of the selected medium (MAY add
                  some sort of translation, scaling, or rotation).

   This attribute primarily controls the translation, scaling and
   rotation of print-stream pages.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.10 orientation-requested (type2 enum)

   This attribute indicates the desired orientation for printed print-
   stream pages; it does not describe the orientation of the client-
   supplied print-stream pages.

   For some document formats (such as 'application/postscript'), the
   desired orientation of the print-stream pages is specified within the
   document data.  This information is generated by a device driver
   prior to the submission of the print job.  Other document formats
   (such as 'text/plain') do not include the notion of desired
   orientation within the document data.  In the latter case it is
   possible for the Printer object to bind the desired orientation to
   the document data after it has been submitted.  It is expected that a
   Printer object would only support "orientations-requested" for some
   document formats (e.g., 'text/plain' or 'text/html') but not others
   (e.g., 'application/postscript').  This is no different than any
   other Job Template attribute since section 4.2, item 1, points out
   that a Printer object may support or not support any Job Template
   attribute based on the document format supplied by the client.
   However, a special mention is made here since it is very likely that
   a Printer object will support "orientation-requested" for only a
   subset of the supported document formats.

   Standard enum values are:

     Value  Symbolic Name and Description

     '3'    'portrait':  The content will be imaged across the short
                  edge of the medium.
     '4'    'landscape':  The content will be imaged across the long
                  edge of the medium.  Landscape is defined to be a
                  rotation of the print-stream page to be imaged by +90
                  degrees with respect to the medium (i.e. anti-
                  clockwise) from the portrait orientation.  Note:  The
                  +90 direction was chosen because simple finishing on
                  the long edge is the same edge whether portrait or
                  landscape
     '5'    'reverse-landscape':  The content will be imaged across the
                  long edge of the medium.  Reverse-landscape is defined
                  to be a rotation of the print-stream page to be imaged
                  by - 90 degrees with respect to the medium (i.e.
                  clockwise) from the portrait orientation.  Note: The '
                  reverse-landscape' value was added because some
                  applications rotate landscape -90 degrees from
                  portrait, rather than +90 degrees.
     '6'    'reverse-portrait':  The content will be imaged across the
                  short edge of the medium.  Reverse-portrait is defined
                  to be a rotation of the print-stream page to be imaged
                  by 180 degrees with respect to the medium from the
                  portrait orientation.  Note: The 'reverse-portrait'
                  value was added for use with the "finishings"
                  attribute in cases where the opposite edge is desired
                  for finishing a portrait document on simple finishing
                  devices that have only one finishing position.  Thus a
                  'text'/plain' portrait document can be stapled "on the
                  right" by a simple finishing device as is common use
                  with some middle eastern languages such as Hebrew.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.11 media (type3 keyword | name(MAX))

   This attribute identifies the medium that the Printer uses for all
   impressions of the Job.

   The values for "media" include medium-names, medium-sizes, input-
   trays and electronic forms so that one attribute specifies the media.

   If a Printer object supports a medium name as a value of this
   attribute, such a medium name implicitly selects an input-tray that
   contains the specified medium.  If a Printer object supports a medium
   size as a value of this attribute, such a medium size implicitly
   selects a medium name that in turn implicitly selects an input-tray
   that contains the medium with the specified size.  If a Printer
   object supports an input-tray as the value of this attribute, such an
   input-tray implicitly selects the medium that is in that input-tray
   at the time the job prints.  This case includes manual-feed input-
   trays.  If a Printer object supports an electronic form as the value
   of this attribute, such an electronic form implicitly selects a
   medium-name that in turn implicitly selects an input-tray that
   contains the medium specified by the electronic form.  The electronic
   form also implicitly selects an image that the Printer MUST merge
   with the document data as its prints each page.

   Standard keyword values are (taken from ISO DPA and the Printer MIB)
   and are listed in section 14. An administrator MAY define additional
   values using the 'name' or 'keyword' attribute syntax, depending on
   implementation.

   There is also an additional Printer attribute named "media-ready"
   which differs from "media-supported" in that legal values only
   include the subset of "media-supported" values that are physically
   loaded and ready for printing with no operator intervention required.
   If an IPP object supports "media-supported", it NEED NOT support
   "media-ready".

   The relationship of this attribute and the other attributes that
   control document processing is described in section 15.3.

4.2.12 printer-resolution (resolution)

   This attribute identifies the resolution that Printer uses for the
   Job.

4.2.13 print-quality (type2 enum)

   This attribute specifies the print quality that the Printer uses for
   the Job.

   The standard enum values are:

     Value  Symbolic Name and Description

     '3'    'draft': lowest quality available on the printer
     '4'    'normal': normal or intermediate quality on the printer
     '5'    'high': highest quality available on the printer

4.3 Job Description Attributes

   The attributes in this section form the attribute group called "job-
   description".  The following table summarizes these attributes.  The
   third column indicates whether the attribute is a REQUIRED attribute
   that MUST be supported by Printer objects.  If it is not indicated as
   REQUIRED, then it is OPTIONAL.  The maximum size in octets for 'text'
   and 'name' attributes is indicated in parenthesizes.

   +----------------------------+----------------------+----------------+
   |      Attribute             |     Syntax           |   REQUIRED?    |
   +----------------------------+----------------------+----------------+
   | job-uri                    | uri                  |  REQUIRED      |
   +----------------------------+----------------------+----------------+
   | job-id                     | integer(1:MAX)       |  REQUIRED      |
   +----------------------------+----------------------+----------------+
   | job-printer-uri            | uri                  |  REQUIRED      |
   +----------------------------+----------------------+----------------+
   | job-more-info              | uri                  |                |
   +----------------------------+----------------------+----------------+
   | job-name                   | name (MAX)           |  REQUIRED      |
   +----------------------------+----------------------+----------------+
   | job-originating-user-name  | name (MAX)           |  REQUIRED      |
   +----------------------------+----------------------+----------------+
   | job-state                  | type1 enum           |  REQUIRED      |
   +----------------------------+----------------------+----------------+
   | job-state-reasons          | 1setOf type2 keyword |                |
   +----------------------------+----------------------+----------------+
   | job-state-message          | text (MAX)           |                |
   +----------------------------+----------------------+----------------+
   | number-of-documents        | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | output-device-assigned     | name (127)           |                |
   +----------------------------+----------------------+----------------+
   | time-at-creation           | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | time-at-processing         | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | time-at-completed          | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | number-of-intervening-jobs | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | job-message-from-operator  | text (127)           |                |
   +----------------------------+----------------------+----------------+
   | job-k-octets               | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | job-impressions            | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+

   +----------------------------+----------------------+----------------+
   |      Attribute             |     Syntax           |   REQUIRED?    |
   +----------------------------+----------------------+----------------+
   | job-media-sheets           | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | job-k-octets-processed     | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | job-impressions-completed  | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | job-media-sheets-completed | integer (0:MAX)      |                |
   +----------------------------+----------------------+----------------+
   | attributes-charset         | charset              |  REQUIRED      |
   +----------------------------+----------------------+----------------+
   | attributes-natural-language| naturalLanguage      |  REQUIRED      |
   +----------------------------+----------------------+----------------+

4.3.1 job-uri (uri)

   This REQUIRED attribute contains the URI for the job.  The Printer
   object, on receipt of a new job, generates a URI which identifies the
   new Job.  The Printer object returns the value of the "job-uri"
   attribute as part of the response to a create request.  The precise
   format of a Job URI is implementation dependent.  If the Printer
   object supports more than one URI and there is some relationship
   between the newly formed Job URI and the Printer object's URI, the
   Printer object uses the Printer URI supplied by the client in the
   create request.  For example, if the create request comes in over a
   secure channel, the new Job URI MUST use the same secure channel.
   This can be guaranteed because the Printer object is responsible for
   generating the Job URI and the Printer object is aware of its
   security configuration and policy as well as the Printer URI used in
   the create request.

   For a description of this attribute and its relationship to "job-id"
   and "job-printer-uri" attribute, see the discussion in section 2.4 on
   "Object Identity".

4.3.2 job-id (integer(1:MAX))

   This REQUIRED attribute contains the ID of the job.  The Printer, on
   receipt of a new job, generates an ID which identifies the new Job on
   that Printer.  The Printer returns the value of the "job-id"
   attribute as part of the response to a create request.  The 0 value
   is not included to allow for compatibility with SNMP index values
   which also cannot be 0.

   For a description of this attribute and its relationship to "job-uri"
   and "job-printer-uri" attribute, see the discussion in section 2.4 on
   "Object Identity".

4.3.3 job-printer-uri (uri)

   This REQUIRED attribute identifies the Printer object that created
   this Job object.  When a Printer object creates a Job object, it
   populates this attribute with the Printer object URI that was used in
   the create request.  This attribute permits a client to identify the
   Printer object that created this Job object when only the Job
   object's URI is available to the client.  The client queries the
   creating Printer object to determine which languages, charsets,
   operations, are supported for this Job.

   For a description of this attribute and its relationship to "job-uri"
   and "job-id" attribute, see the discussion in section 2.4 on "Object
   Identity".

4.3.4 job-more-info (uri)

   Similar to "printer-more-info", this attribute contains the URI
   referencing some resource with more information about this Job
   object, perhaps an HTML page containing information about the Job.

4.3.5 job-name (name(MAX))

   This REQUIRED attribute is the name of the job.  It is a name that is
   more user friendly than the "job-uri" attribute value.  It does not
   need to be unique between Jobs.  The Job's "job-name" attribute is
   set to the value supplied by the client in the "job-name" operation
   attribute in the create request (see Section 3.2.1.1).   If, however,
   the "job-name" operation attribute is not supplied by the client in
   the create request, the Printer object, on creation of the Job, MUST
   generate a name.  The printer SHOULD generate the value of the Job's
   "job-name" attribute from the first of the following sources that
   produces a value: 1) the "document-name" operation attribute of the
   first (or only) document, 2) the "document-URI" attribute of the
   first (or only) document, or 3) any other piece of Job specific
   and/or Document Content information.

4.3.6 job-originating-user-name (name(MAX))

   This REQUIRED attribute contains the name of the end user that
   submitted the print job.  The Printer object sets this attribute to
   the most authenticated printable name that it can obtain from the
   authentication service over which the IPP operation was received.

   Only if such is not available, does the Printer object use the value
   supplied by the client in the "requesting-user-name" operation
   attribute of the create operation (see Section 8).

   Note:  The Printer object needs to keep an internal originating user
   id of some form, typically as a credential of a principal, with the
   Job object.  Since such an internal attribute is implementation-
   dependent and not of interest to clients, it is not specified as a
   Job Description attribute.  This originating user id is used for
   authorization checks (if any) on all subsequent operation.

4.3.7 job-state (type1 enum)

   This REQUIRED attribute identifies the current state of the job.
   Even though the IPP protocol defines eight values for job states,
   implementations only need to support those states which are
   appropriate for the particular implementation.  In other words, a
   Printer supports only those job states implemented by the output
   device and available to the Printer object implementation.

   Standard enum values are:

     Values Symbolic Name and Description

     '3'    'pending':  The job is a candidate to start processing, but
                  is not yet processing.

     '4'    'pending-held':  The job is not a candidate for processing
                  for any number of reasons but will return to the '
                  pending' state as soon as the reasons are no longer
                  present.  The job's "job-state-reason" attribute MUST
                  indicate why the job is no longer a candidate for
                  processing.

     '5'    'processing':  One or more of:

                  1.  the job is using, or is attempting to use, one or
                  more purely software processes that are analyzing,
                  creating, or interpreting a PDL, etc.,
                  2.  the job is using, or is attempting to use, one or
                  more hardware devices that are interpreting a PDL,
                  making marks on a medium, and/or performing finishing,
                  such as stapling, etc.,
                  3. the Printer object has made the job ready for
                  printing, but the output device is not yet printing
                  it, either because the job hasn't reached the output

                  device or because the job is queued in the output
                  device or some other spooler, awaiting the output
                  device to print it.

                  When the job is in the 'processing' state, the entire
                  job state includes the detailed status represented in
                  the printer's "printer-state", "printer-state-
                  reasons", and "printer-state-message" attributes.

                  Implementations MAY, though they NEED NOT,  include
                  additional values in the job's "job-state-reasons"
                  attribute to indicate the progress of the job, such as
                  adding the 'job-printing' value to indicate when the
                  output device is actually making marks on paper and/or
                  the 'processing-to-stop-point' value to indicate that
                  the IPP object is in the process of canceling or
                  aborting the job.  Most implementations won't bother
                  with this nuance.

     '6'    'processing-stopped':  The job has stopped while processing
                  for any number of reasons and will return to the '
                  processing' state as soon as the reasons are no longer
                  present.

                  The job's "job-state-reason" attribute MAY indicate
                  why the job has stopped processing.  For example, if
                  the output device is stopped, the 'printer-stopped'
                  value MAY be included in the job's "job-state-reasons"
                  attribute.

                  Note:  When an output device is stopped, the device
                  usually indicates its condition in human readable form
                  locally at the device.  A client can obtain more
                  complete device status remotely by querying the
                  Printer object's "printer-state", "printer-state-
                  reasons" and "printer-state-message" attributes.

     '7'    'canceled':  The job has been canceled by a Cancel-Job
                  operation and the Printer object has completed
                  canceling the job and all job status attributes have
                  reached their final values for the job.  While the
                  Printer object is canceling the job, the job remains
                  in its current state, but the job's "job-state-
                  reasons" attribute SHOULD contain the 'processing-to-
                  stop-point' value and one of the 'canceled-by-user', '
                  canceled-by-operator', or 'canceled-at-device' value.

                  When the job moves to the 'canceled' state, the '
                  processing-to-stop-point' value, if present, MUST be
                  removed, but the 'canceled-by-xxx', if present, MUST
                  remain.

     '8'    'aborted':  The job has been aborted by the system, usually
                  while the job was in the 'processing' or 'processing-
                  stopped' state and the Printer has completed aborting
                  the job and all job status attributes have reached
                  their final values for the job.  While the Printer
                  object is aborting the job, the job remains in its
                  current state, but the job's "job-state-reasons"
                  attribute SHOULD contain the 'processing-to-stop-
                  point' and 'aborted-by-system' values.  When the job
                  moves to the 'aborted' state, the  'processing-to-
                  stop-point' value, if present, MUST be removed, but
                  the 'aborted-by-system' value, if present, MUST
                  remain.

     '9'    'completed':  The job has completed successfully or with
                  warnings or errors after processing and all of the job
                  media sheets have been successfully stacked in the
                  appropriate output bin(s) and all job status
                  attributes have reached their final values for the
                  job.  The job's "job-state-reasons" attribute SHOULD
                  contain one of:  'completed-successfully', '
                  completed-with-warnings', or 'completed-with-errors'
                  values.

   The final value for this attribute MUST be one of: 'completed', '
   canceled', or 'aborted' before the Printer removes the job
   altogether.  The length of time that jobs remain in the 'canceled', '
   aborted', and 'completed' states depends on implementation.

   The following figure shows the normal job state transitions.

                                                      +----> canceled
                                                     /
       +----> pending --------> processing ---------+------> completed
       |         ^                   ^               \
   --->+         |                   |                +----> aborted
       |         v                   v               /
       +----> pending-held    processing-stopped ---+

   Normally a job progresses from left to right.  Other state
   transitions are unlikely, but are not forbidden.  Not shown are the
   transitions to the 'canceled' state from the 'pending', 'pending-
   held', and 'processing-stopped' states.

   Jobs reach one of the three terminal states: 'completed', 'canceled',
   or 'aborted', after the jobs have completed all activity, including
   stacking output media, after the jobs have completed all activity,
   and all job status attributes have reached their final values for the
   job.

   Note: As with all other IPP attributes, if the implementation can not
   determine the correct value for this attribute, it SHOULD respond
   with the out-of-band value 'unknown' (see section 4.1) rather than
   try to guess at some possibly incorrect value and give the end user
   the wrong impression about the state of the Job object.  For example,
   if the implementation is just a gateway into some printing system
   that does not provide detailed status about the print job, the IPP
   Job object's state might literally be 'unknown'.

4.3.8 job-state-reasons (1setOf  type2 keyword)

   This attribute provides additional information about the job's
   current state, i.e., information that augments the value of the job's
   "job-state" attribute.

   Implementation of these values is OPTIONAL, i.e., a Printer NEED NOT
   implement them, even if (1) the output device supports the
   functionality represented by the reason and (2) is available to the
   Printer object implementation.  These values MAY be used with any job
   state or states for which the reason makes sense.  Furthermore, when
   implemented, the Printer MUST return these values when the reason
   applies and MUST NOT return them when the reason no longer applies
   whether the value of the Job's "job-state" attribute changed or not.
   When the Job does not have any reasons for being in its current
   state, the value of the Job's "job-state-reasons" attribute MUST be '
   none'.

   Note: While values cannot be added to the 'job-state' attribute
   without impacting deployed clients that take actions upon receiving
   "job-state" values, it is the intent that additional "job-state-
   reasons" values can be defined and registered without impacting such
   deployed clients.  In other words, the "job-state-reasons" attribute
   is intended to be extensible.

   The following standard keyword values are defined.  For ease of
   understanding, the values are presented in the order in which the
   reasons are likely to occur (if implemented), starting with the '
   job-incoming' value:

     'none':  There are no reasons for the job's current state.
     'job-incoming':  The Create-Job operation has been accepted by the
        Printer, but the Printer is expecting additional Send-Document

        and/or Send-URI operations and/or is accessing/accepting
        document data.
     'submission-interrupted':  The job was not completely submitted for
        some unforeseen reason, such as: (1) the Printer has crashed
        before the job was closed by the client, (2) the Printer or the
        document transfer method has crashed in some non-recoverable way
        before the document data was entirely transferred to the
        Printer, (3) the client crashed or failed to close the job
        before the time-out period.  See section 4.4.28.
     'job-outgoing':  The Printer is transmitting the job to the output
        device.
     'job-hold-until-specified':  The value of the job's "job-hold-
        until" attribute was specified with a time period that is still
        in the future.  The job MUST NOT be a candidate for processing
        until this reason is removed and there are no other reasons to
        hold the job.
     'resources-are-not-ready':  At least one of the resources needed by
        the job, such as media, fonts, resource objects, etc., is not
        ready on any of the physical printer's for which the job is a
        candidate.  This condition MAY be detected when the job is
        accepted, or subsequently while the job is pending or
        processing, depending on implementation.  The job may remain in
        its current state or be moved to the 'pending-held' state,
        depending on implementation and/or job scheduling policy.
     'printer-stopped-partly':  The value of the Printer's "printer-
        state-reasons" attribute contains the value 'stopped-partly'.
     'printer-stopped':  The value of the Printer's "printer-state"
        attribute is 'stopped'.
     'job-interpreting': Job is in the 'processing' state, but more
        specifically, the Printer is interpreting the document data.
     'job-queued': Job is in the 'processing' state, but more
        specifically, the Printer has queued the document data.
     'job-transforming': Job is in the 'processing' state, but more
        specifically, the Printer is interpreting document data and
        producing another electronic representation.
     'job-printing':  The output device is marking media. This value is
        useful for Printers which spend a great deal of time processing
        (1) when no marking is happening and then want to show that
        marking is now happening or (2) when the job is in the process
        of being canceled or aborted while the job remains in the '
        processing' state, but the marking has not yet stopped so that
        impression or sheet counts are still increasing for the job.
     'job-canceled-by-user':  The job was canceled by the owner of the
        job using the Cancel-Job request, i.e., by a user whose
        authenticated identity is the same as the value of the
        originating user that created the Job object, or by some other
        authorized end-user, such as a member of the job owner's
        security group.

     'job-canceled-by-operator':  The job was canceled by the operator
        using the Cancel-Job request, i.e., by a user who has been
        authenticated as having operator privileges (whether local or
        remote).  If the security policy is to allow anyone to cancel
        anyone's job, then this value may be used when the job is
        canceled by other than the owner of the job.  For such a
        security policy, in effect, everyone is an operator as far as
        canceling jobs with IPP is concerned.
     'job-canceled-at-device':  The job was canceled by an unidentified
        local user, i.e., a user at a console at the device.
     'aborted-by-system':  The job (1) is in the process of being
        aborted, (2) has been aborted by the system and placed in the '
        aborted' state, or (3) has been aborted by the system and placed
        in the 'pending-held' state, so that a user or operator can
        manually try the job again.
     'processing-to-stop-point':  The requester has issued a Cancel-Job
        operation or the Printer object has aborted the job, but is
        still performing some actions on the job until a specified stop
        point occurs or job termination/cleanup is completed.

        This reason is recommended to be used in conjunction with the '
        processing' job state to indicate that the Printer object is
        still performing some actions on the job while the job remains
        in the 'processing' state.  After all the job's job description
        attributes have stopped incrementing, the Printer object moves
        the job from the 'processing' state to the 'canceled' or '
        aborted' job states.

     'service-off-line':  The Printer is off-line and accepting no jobs.
        All 'pending' jobs are put into the 'pending-held' state.  This
        situation could be true if the service's or document transform's
        input is impaired or broken.
     'job-completed-successfully':  The job completed successfully.
     'job-completed-with-warnings':  The job completed with warnings.
     'job-completed-with-errors':  The job completed with errors (and
        possibly warnings too).

4.3.9 job-state-message (text(MAX))

   This attribute specifies information about the "job-state" and "job-
   state-reasons" attributes in human readable text.  If the Printer
   object supports this attribute, the Printer object MUST be able to
   generate this message in any of the natural languages identified by
   the Printer's "generated-natural-language-supported" attribute (see
   the "attributes-natural-language" operation attribute specified in
   Section 3.1.4.1).

   Note:  the value SHOULD NOT contain additional information not
   contained in the values of the "job-state" and "job-states-reasons"
   attributes, such as interpreter error information.  Otherwise,
   application programs might attempt to parse the (localized text).
   For such additional information such as interpreter errors for
   application program consumption, a new attribute with keyword values,
   needs to be developed and registered.

4.3.10 number-of-documents (integer(0:MAX))

   This attribute indicates the number of documents in the job, i.e.,
   the number of Send-Document, Send-URI, Print-Job, or Print-URI
   operations that the Printer has accepted for this job, regardless of
   whether the document data has reached the Printer object or not.

   Implementations supporting the OPTIONAL Create-Job/Send-
   Document/Send-URI operations SHOULD support this attribute so that
   clients can query the number of documents in each job.

4.3.11 output-device-assigned (name(127))

   This attribute identifies the output device to which the Printer
   object has assigned this job.  If an output device implements an
   embedded Printer object, the Printer object NEED NOT set this
   attribute.  If a print server implements a Printer object, the value
   MAY be empty (zero-length string) or not returned until the Printer
   object assigns an output device to the job.  This attribute is
   particularly useful when a single Printer object support multiple
   devices (so called "fan-out").

4.3.12 time-at-creation (integer(0:MAX))

   This attribute indicates the point in time at which the Job object
   was created.  In order to populate this attribute, the Printer object
   uses the value in its "printer-up-time" attribute at the time the Job
   object is created.

4.3.13 time-at-processing (integer(0:MAX))

   This attribute indicates the point in time at which the Job object
   began processing.  In order to populate this attribute, the Printer
   object uses the value in its "printer-up-time" attribute at the time
   the Job object is moved into the 'processing' state for the first
   time.

4.3.14 time-at-completed (integer(0:MAX))

   This attribute indicates the point in time at which the Job object
   completed (or was cancelled or aborted).  In order to populate this
   attribute, the Printer object uses the value in its "printer-up-time"
   attribute at the time the Job object is moved into the 'completed' or
   'canceled' or 'aborted' state.

4.3.15 number-of-intervening-jobs (integer(0:MAX))

   This attribute indicates the number of jobs that are "ahead" of this
   job in the relative chronological order of expected time to complete
   (i.e., the current scheduled order). For efficiency, it is only
   necessary to calculate this value when an operation is performed that
   requests this attribute.

4.3.16 job-message-from-operator (text(127))

   This attribute provides a message from an operator, system
   administrator or "intelligent" process to indicate to the end user
   the reasons for modification or other management action taken on a
   job.

4.3.17 job-k-octets (integer(0:MAX))

   This attribute specifies the total size of the document(s) in K
   octets, i.e., in units of 1024 octets requested to be processed in
   the job.  The value MUST be rounded up, so that a job between 1 and
   1024 octets MUST be indicated as being 1, 1025 to 2048 MUST be 2,
   etc.

   This value MUST NOT include the multiplicative factors contributed by
   the number of copies specified by the "copies" attribute, independent
   of whether the device can process multiple copies without making
   multiple passes over the job or document data and independent of
   whether the output is collated or not.  Thus the value is independent
   of the implementation and indicates the size of the document(s)
   measured in K octets independent of the number of copies.

   This value MUST also not include the multiplicative factor due to a
   copies instruction embedded in the document data.  If the document
   data actually includes replications of the document data, this value
   will include such replication.  In other words, this value is always
   the size of the source document data, rather than a measure of the
   hardcopy output to be produced.

   Note: This attribute and the following two attributes ("job-
   impressions" and "job-media-sheets") are not intended to be counters;
   they are intended to be useful routing and scheduling information if
   known.  For these three attributes, the Printer object may try to
   compute the value if it is not supplied in the create request.  Even
   if the client does supply a value for these three attributes in the
   create request, the Printer object MAY choose to change the value if
   the Printer object is able to compute a value which is more accurate
   than the client supplied value.  The Printer object may be able to
   determine the correct value for these three attributes either right
   at job submission time or at any later point in time.

4.3.18 job-impressions (integer(0:MAX))

   This attribute specifies the total size in number of impressions of
   the document(s) being submitted (see the definition of impression in
   section 13.2.5).

   As with "job-k-octets", this value MUST NOT include the
   multiplicative factors contributed by the number of copies specified
   by the "copies" attribute, independent of whether the device can
   process multiple copies without making multiple passes over the job
   or document data and independent of whether the output is collated or
   not.  Thus the value is independent of the implementation and
   reflects the size of the document(s) measured in impressions
   independent of the number of copies.

   As with "job-k-octets", this value MUST also not include the
   multiplicative factor due to a copies instruction embedded in the
   document data.  If the document data actually includes replications
   of the document data, this value will include such replication.  In
   other words, this value is always the number of impressions in the
   source document data, rather than a measure of the number of
   impressions to be produced by the job.

   See the Note in the "job-k-octets" attribute that also applies to
   this attribute.

4.3.19 job-media-sheets (integer(0:MAX))

   This attribute specifies the total number of media sheets to be
   produced for this job.

   Unlike the "job-k-octets" and the "job-impressions" attributes, this
   value MUST include the multiplicative factors contributed by the
   number of copies specified by the "copies" attribute and a 'number of
   copies' instruction embedded in the document data, if any.  This
   difference allows the system administrator to control the lower and

   upper bounds of both (1) the size of the document(s) with "job-k-
   octets-supported" and "job-impressions-supported" and (2) the size of
   the job with "job-media-sheets-supported".

   See the Note in the "job-k-octets" attribute that also applies to
   this attribute.

4.3.20 job-k-octets-processed (integer(0:MAX))

   This attribute specifies the total number of octets processed in K
   octets, i.e., in units of 1024 octets so far.  The value MUST be
   rounded up, so that a job between 1 and 1024 octets inclusive MUST be
   indicated as being 1, 1025 to 2048 inclusive MUST be 2, etc.

   For implementations where multiple copies are produced by the
   interpreter with only a single pass over the data, the final value
   MUST be equal to the value of the "job-k-octets" attribute.  For
   implementations where multiple copies are produced by the interpreter
   by processing the data for each copy, the final value MUST be a
   multiple of the value of the "job-k-octets" attribute.

   Note: This attribute and the following two attributes ("job-
   impressions-completed" and "job-sheets-completed") are intended to be
   counters. That is, the value for a job that has not started
   processing MUST be 0.  When the job's "job-state" is 'processing' or
   'processing-stopped', this value is intended to contain the amount of
   the job that has been processed to the time at which the attributes
   are requested.

4.3.21 job-impressions-completed (integer(0:MAX))

   This job attribute specifies the number of impressions completed for
   the job so far.  For printing devices, the impressions completed
   includes interpreting, marking, and stacking the output.

   See the note in "job-k-octets-processed" which also applies to this
   attribute.

4.3.22 job-media-sheets-completed (integer(0:MAX))

   This job attribute specifies the media-sheets completed marking and
   stacking for the entire job so far whether those sheets have been
   processed on one side or on both.

   See the note in "job-k-octets-processed" which also applies to this
   attribute.

4.3.23 attributes-charset (charset)

   This REQUIRED attribute is populated using the value in the client
   supplied "attributes-charset" attribute in the create request.  It
   identifies the charset (coded character set and encoding method) used
   by any Job attributes with attribute syntax 'text' and 'name' that
   were supplied by the client in the create request.  See Section 3.1.4
   for a complete description of the "attributes-charset" operation
   attribute.

   This attribute does not indicate the charset in which the 'text' and
   'name' values are stored internally in the Job object.  The internal
   charset is implementation-defined.  The IPP object MUST convert from
   whatever the internal charset is to that being requested in an
   operation as specified in Section 3.1.4.

4.3.24 attributes-natural-language (naturalLanguage)

   This REQUIRED attribute is populated using the value in the client
   supplied "attributes-natural-language" attribute in the create
   request.  It identifies the natural language used for any Job
   attributes with attribute syntax 'text' and 'name' that were supplied
   by the client in the create request.  See Section 3.1.4 for a
   complete description of the "attributes-natural-language" operation
   attribute.  See Sections 4.1.1.2 and 4.1.2.2 for how a Natural
   Language Override may be supplied explicitly for each 'text' and '
   name' attribute value that differs from the value identified by the
   "attributes-natural-language" attribute.

4.4 Printer Description Attributes

   These attributes form the attribute group called "printer-
   description".  The following table summarizes these attributes, their
   syntax, and whether or not they are REQUIRED for a Printer object to
   support.  If they are not indicated as REQUIRED, they are OPTIONAL.
   The maximum size in octets for 'text' and 'name' attributes is
   indicated in parenthesizes.

   Note: How these attributes are set by an Administrator is outside the
   scope of this specification.

  +----------------------------+----------------------+----------------+
  |      Attribute             |     Syntax           |   REQUIRED?    |
  +----------------------------+----------------------+----------------+
  | printer-uri-supported      | 1setOf uri           |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | uri-security-supported     | 1setOf type2 keyword |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | printer-name               | name (127)           |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | printer-location           | text (127)           |                |
  +----------------------------+----------------------+----------------+
  | printer-info               | text (127)           |                |
  +----------------------------+----------------------+----------------+
  | printer-more-info          | uri                  |                |
  +----------------------------+----------------------+----------------+
  | printer-driver-installer   | uri                  |                |
  +----------------------------+----------------------+----------------+
  | printer-make-and-model     | text (127)           |                |
  +----------------------------+----------------------+----------------+
  | printer-more-info-         | uri                  |                |
  | manufacturer               |                      |                |
  +----------------------------+----------------------+----------------+
  | printer-state              | type1 enum           |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | printer-state-reasons      | 1setOf type2 keyword |                |
  +----------------------------+----------------------+----------------+
  | printer-state-message      | text (MAX)           |                |
  +----------------------------+----------------------+----------------+
  | operations-supported       | 1setOf type2 enum    |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | charset-configured         | charset              |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | charset-supported          | 1setOf charset       |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | natural-language-configured| naturalLanguage      |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | generated-natural-language-| 1setOf               |  REQUIRED      |
  | supported                  |   naturalLanguage    |                |
  +----------------------------+----------------------+----------------+
  | document-format-default    | mimeMediaType        |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | document-format-           | 1setOf               |  REQUIRED      |
  |   supported                |   mimeMediaType      |                |
  +----------------------------+----------------------+----------------+
  | printer-is-accepting-jobs  | boolean              |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | queued-job-count           | integer (0:MAX)      |  RECOMMENDED   |
  +----------------------------+----------------------+----------------+

  +----------------------------+----------------------+----------------+
  |      Attribute             |     Syntax           |   REQUIRED?    |
  +----------------------------+----------------------+----------------+
  | printer-message-from-      | text (127)           |                |
  | operator                   |                      |                |
  +----------------------------+----------------------+----------------+
  | color-supported            | boolean              |                |
  +----------------------------+----------------------+----------------+
  | reference-uri-schemes-     | 1setOf uriScheme     |                |
  |   supported                |                      |                |
  +----------------------------+----------------------+----------------+
  | pdl-override-supported     | type2 keyword        |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | printer-up-time            | integer (1:MAX)      |  REQUIRED      |
  +----------------------------+----------------------+----------------+
  | printer-current-time       | dateTime             |                |
  +----------------------------+----------------------+----------------+
  | multiple-operation-time-out| integer (1:MAX)      |                |
  +----------------------------+----------------------+----------------+
  | compression-supported      | 1setOf type3 keyword |                |
  +----------------------------+----------------------+----------------+
  | job-k-octets-supported     | rangeOfInteger       |                |
  |                            |    (0:MAX)           |                |
  +----------------------------+----------------------+----------------+
  | job-impressions-supported  | rangeOfInteger       |                |
  |                            |    (0:MAX)           |                |
  +----------------------------+----------------------+----------------+
  | job-media-sheets-supported | rangeOfInteger       |                |
  |                            |    (0:MAX)           |                |
  +----------------------------+----------------------+----------------+

4.4.1 printer-uri-supported (1setOf uri)

   This REQUIRED Printer attribute contains at least one URI for the
   Printer object.  It OPTIONALLY contains more than one URI for the
   Printer object.    An administrator determines a Printer object's
   URI(s) and configures this attribute to contain those URIs by some
   means outside the scope of IPP/1.0.  The precise format of this URI
   is implementation dependent and depends on the protocol.  See the
   next section for a description "uri-security-supported" which is the
   REQUIRED companion attribute to this "printer-uri-supported"
   attribute.  See section 2.4 on Printer object identity and section
   8.2 on security and URIs for more information.

4.4.2 uri-security-supported (1setOf type2 keyword)

   This REQUIRED Printer attribute MUST have the same cardinality
   (contain the same number of values) as the "printer-uri-supported"
   attribute.  This attribute identifies the security mechanisms used
   for each URI listed in the "printer-uri-supported" attribute.  The "i
   th" value in "uri-security-supported" corresponds to the "i th" value
   in "printer-uri-supported" and it describes the security mechanisms
   used for accessing the Printer object via that URI. The following
   standard values are defined:

     'none': There are no secure communication channel protocols in use
        for the given URI.

     'ssl3': SSL3 [SSL] is the secure communications channel protocol in
        use for the given URI.

   Consider the following example.  For a single Printer object, an
   administrator configures the "printer-uri-supported" and "uri-
   security-supported" attributes as follows:

     "printer-uri-supported": 'http://acme.com/open-use-printer', '
        http://acme.com/restricted-use-printer', '
        http://acme.com/private-printer'
     "uri-security-supported": 'none', 'none', 'ssl3'

   In this case, one Printer object has three URIs.

     - For the first URI, 'http://acme.com/open-use-printer', the value
        'none' in "uri-security-supported" indicates that there is no
        secure channel protocol configured to run under HTTP.  The name
        implies that there is no Basic or Digest authentication being
        used, but it is up to the client to determine that while using
        HTTP underneath the IPP application protocol.
     - For the second URI, 'http://acme.com/restricted-use-printer', the
        value 'none' in "uri-security-supported" indicates that there is
        no secure channel protocol configured to run under HTTP.  In
        this case, although the name does imply that there is some sort
        of Basic or Digest authentication being used within HTTP, it is
        up to the client to determine that while using HTTP and by
        processing any '401 Unauthorized' HTTP error messages.
     - For the third URI, 'http://acme.com/private-printer', the value '
        ssl3' in "uri-security-supported" indicates that SSL3 is being
        used to secure the channel.  The client SHOULD be prepared to
        use SSL3 framing to negotiate an acceptable ciphersuite to use
        while communicating with the Printer object.  In this case, the
        name implies the use of a secure communications channel, but the
        fact is made explicit by the presence of the 'ssl3' value in

        "uri-security-supported".  The client does not need to resort to
        understanding which security it must use by following naming
        conventions or by parsing the URI to determine which security
        mechanisms are implied.

   It is expected that many IPP Printer objects will be configured to
   support only one channel (either configured to use SSL3 access or
   not), and will therefore only ever have one URI listed in the
   "printer-uri-supported" attribute.  No matter the configuration of
   the Printer object (whether it has only one URI or more than one
   URI), a client MUST supply only one URI in the target "printer-uri"
   operation attribute.

4.4.3 printer-name (name(127))

   This REQUIRED Printer attribute contains the name of the Printer
   object.  It is a name that is more end-user friendly than a URI. An
   administrator determines a printer's name and sets this attribute to
   that name. This name may be the last part of the printer's URI or it
   may be unrelated.  In non-US-English locales, a name may contain
   characters that are not allowed in a URI.

4.4.4 printer-location (text(127))

   This Printer attribute identifies the location of the device. This
   could include things like: "in Room 123A, second floor of building
   XYZ".

4.4.5 printer-info (text(127))

   This Printer attribute identifies the descriptive information about
   this Printer object.  This could include things like: "This printer
   can be used for printing color transparencies for HR presentations",
   or "Out of courtesy for others, please print only small (1-5 page)
   jobs at this printer", or even "This printer is going away on July 1,
   1997, please find a new printer".

4.4.6 printer-more-info (uri)

   This Printer attribute contains a URI used to obtain more information
   about this specific Printer object.  For example, this could be an
   HTTP type URI referencing an HTML page accessible to a Web Browser.
   The information obtained from this URI is intended for end user
   consumption.  Features outside the scope of IPP can be accessed from
   this URI.  The information is intended to be specific to this printer
   instance and site specific services (e.g. job pricing, services
   offered, end user assistance). The device manufacturer may initially
   populate this attribute.

4.4.7 printer-driver-installer (uri)

   This Printer attribute contains a URI to use to locate the driver
   installer for this Printer object.   This attribute is intended for
   consumption by automata.  The mechanics of print driver installation
   is outside the scope of IPP.  The device manufacturer may initially
   populate this attribute.

4.4.8 printer-make-and-model (text(127))

   This Printer attribute identifies the make and model of the device.
   The device manufacturer may initially populate this attribute.

4.4.9 printer-more-info-manufacturer (uri)

   This Printer attribute contains a URI used to obtain more information
   about this type of device.  The information obtained from this URI is
   intended for end user consumption.  Features outside the scope of IPP
   can be accessed from this URI (e.g., latest firmware, upgrades, print
   drivers, optional features available, details on color support).  The
   information is intended to be germane to this printer without regard
   to site specific modifications or services. The device manufacturer
   may initially populate this attribute.

4.4.10 printer-state (type1 enum)

   This REQUIRED Printer attribute identifies the current state of the
   device.  The "printer-state reasons" attribute augments the
   "printer-state" attribute to give more detailed information about the
   Printer in the given printer state.

   A Printer object need only update this attribute before responding to
   an operation which requests the attribute; the Printer object NEED
   NOT update this attribute continually, since asynchronous event
   notification is not part of IPP/1.0.  A Printer NEED NOT implement
   all values if they are not applicable to a given implementation.

   The following standard enum values are defined:

     Value  Symbolic Name and Description

     '3'    'idle':  If a Printer receives a job (whose required
                  resources are ready) while in this state, such a job
                  MUST transit into the 'processing' state immediately.
                  If the "printer-state-reasons" attribute contains any
                  reasons, they MUST be reasons that would not prevent a
                  job from transiting into the 'processing' state
                  immediately, e.g., 'toner-low'. Note: if a Printer

                  controls more than one output device, the above
                  definition implies that a Printer is 'idle' if at
                  least one output device is idle.

     '4'    'processing':  If a Printer receives a job (whose required
                  resources are ready) while in this state, such a job
                  MUST transit into the 'pending' state immediately.
                  Such a job MUST transit into the 'processing' state
                  only after jobs ahead of it complete.  If the
                  "printer-state-reasons" attribute contains any
                  reasons, they MUST be reasons that do not prevent the
                  current job from printing, e.g.  'toner-low'.  Note:
                  if a Printer controls more than one output device, the
                  above definition implies that a Printer is '
                  processing' if at least one output device is
                  processing, and none is idle.

     '5'    'stopped':  If a Printer receives a job (whose required
                  resources are ready) while in this state, such a job
                  MUST transit into the 'pending' state immediately.
                  Such a job MUST transit into the 'processing' state
                  only after some human fixes the problem that stopped
                  the printer and after jobs ahead of it complete
                  processing.  If supported, the "printer-state-reasons"
                  attribute MUST contain at least one reason, e.g. '
                  media-jam', which prevents it from either processing
                  the current job or transitioning a 'pending' job to
                  the 'processing' state.

                  Note: if a Printer controls more than one output
                  device, the above definition implies that a Printer is
                  'stopped' only if all output devices are stopped.
                  Also, it is tempting to define 'stopped' as when a
                  sufficient number of output devices are stopped and
                  leave it to an implementation to define the sufficient
                  number.  But such a rule complicates the definition of
                  'stopped' and 'processing'. For example, with this
                  alternate definition of 'stopped', a job can move from
                  'pending' to 'processing' without human intervention,
                  even though the Printer is stopped.

4.4.11 printer-state-reasons (1setOf type2 keyword)

   This Printer attribute supplies additional detail about the device's
   state.

   Each keyword value MAY have a suffix to indicate its level of
   severity.  The three levels are: report (least severe), warning, and
   error (most severe).

     - '-report':  This suffix indicates that the reason is a "report".
        An implementation may choose to omit some or all reports. Some
        reports specify finer granularity about the printer state;
        others serve as a precursor to a warning. A report MUST contain
        nothing that could affect the printed output.
     - '-warning': This suffix indicates that the reason is a "warning".
        An implementation may choose to omit some or all warnings.
        Warnings serve as a precursor to an error. A warning MUST
        contain nothing that prevents a job from completing, though in
        some cases the output may be of lower quality.
     - '-error': This suffix indicates that the reason is an "error".
        An implementation MUST include all errors. If this attribute
        contains one or more errors, printer MUST be in the stopped
        state.

   If the implementation does not add any one of the three suffixes, all
   parties MUST assume that the reason is an "error".

   If a Printer object controls more than one output device, each value
   of this attribute MAY apply to one or more of the output devices.  An
   error on one output device that does not stop the Printer object as a
   whole MAY appear as a warning in the Printer's "printer-state-reasons
   attribute".  If the "printer-state" for such a Printer has a value of
   'stopped', then there MUST be an error reason among the values in the
   "printer-state-reasons" attribute.

   The following standard keyword values are defined:

     'other': The device has detected an error other than one listed in
        this document.
     'none': There are not reasons. This state reason is semantically
        equivalent to "printer-state-reasons" without any value.
     'media-needed': A tray has run out of media.
     'media-jam': The device has a media jam.
     'paused': Someone has paused the Printer object.  In this state, a
        Printer MUST NOT produce printed output, but it MUST perform
        other operations requested by a client.  If a Printer had been
        printing a job when the Printer was paused, the Printer MUST
        resume printing that job when the Printer is no longer paused
        and leave no evidence in the printed output of such a pause.
     'shutdown': Someone has removed a Printer object from service, and
        the device may be powered down or physically removed.  In this
        state, a Printer object MUST NOT produce printed output, and
        unless the Printer object is realized by a print server that is

        still active, the Printer object MUST perform no other
        operations requested by a client, including returning this
        value. If a Printer object had been printing a job when it was
        shutdown, the Printer NEED NOT resume printing that job when the
        Printer is no longer shutdown. If the Printer resumes printing
        such a job, it may leave evidence in the printed output of such
        a shutdown, e.g. the part printed before the shutdown may be
        printed a second time after the shutdown.
     'connecting-to-device': The Printer object has scheduled a job on
        the output device and is in the process of connecting to a
        shared network output device (and might not be able to actually
        start printing the job for an arbitrarily long time depending on
        the usage of the output device by other servers on the network).
     'timed-out': The server was able to connect to the output device
        (or is always connected), but was unable to get a response from
        the output device.
     'stopping': The Printer object is in the process of stopping the
        device and will be stopped in a while. When the device is
        stopped, the Printer object will change the Printer object's
        state to 'stopped'.  The 'stopping-warning' reason is never an
        error, even for a Printer with a single output device.  When an
        output-device ceases accepting jobs, the Printer will have this
        reason while the output device completes printing.
     'stopped-partly': When a Printer object controls more than one
        output device, this reason indicates that one or more output
        devices are stopped.  If the reason is a report, fewer than half
        of the output devices are stopped.  If the reason is a warning,
        fewer than all of the output devices are stopped.
     'toner-low': The device is low on toner.
     'toner-empty': The device is out of toner.
     'spool-area-full': The limit of persistent storage allocated for
        spooling has been reached.
     'cover-open': One or more covers on the device are open.
     'interlock-open': One or more interlock devices on the printer are
        unlocked.
     'door-open': One or more doors on the device are open.
     'input-tray-missing': One or more input trays are not in the
        device.
     'media-low': At least one input tray is low on media.
     'media-empty': At least one input tray is empty.
     'output-tray-missing': One or more output trays are not in the
        device
     'output-area-almost-full': One or more output area is almost full
        (e.g. tray, stacker, collator).
     'output-area-full': One or more output area is full. (e.g. tray,
        stacker, collator)
     'marker-supply-low': The device is low on at least one marker
        supply.  (e.g. toner, ink, ribbon)

     'marker-supply-empty: The device is out of at least one marker
        supply. (e.g. toner, ink, ribbon)
     'marker-waste-almost-full': The device marker supply waste
        receptacle is almost full.
     'marker-waste-full': The device marker supply waste receptacle is
        full.
     'fuser-over-temp': The fuser temperature is above normal.
     'fuser-under-temp': The fuser temperature is below normal.
     'opc-near-eol': The optical photo conductor is near end of life.
     'opc-life-over': The optical photo conductor is no longer
        functioning.
     'developer-low': The device is low on developer.
     'developer-empty: The device is out of developer.
     'interpreter-resource-unavailable': An interpreter resource is
        unavailable (i.e. font, form)

4.4.12 printer-state-message (text(MAX))

   This Printer attribute specifies the additional information about the
   printer state and printer state reasons in human readable text.  If
   the Printer object supports this attribute, the Printer object MUST
   be able to generate this message in any of the natural languages
   identified by the Printer's "generated-natural-language-supported"
   attribute (see the "attributes-natural-language" operation attribute
   specified in Section 3.1.4.1).

4.4.13 operations-supported (1setOf type2 enum)

   This REQUIRED Printer attribute specifies the set of supported
   operations for this Printer object and contained Job objects.  All
   32-bit enum values for this attribute MUST NOT exceed 0x8FFF, since
   these values are passed in two octets in each Protocol request
   [RFC2565].

   The following standard enum and "operation-id" (see section 3.1.2)
   values are defined:

     Value               Operation Name
     -----------------   -------------------------------------

     0x0000              reserved, not used
     0x0001              reserved, not used
     0x0002              Print-Job
     0x0003              Print-URI
     0x0004              Validate-Job
     0x0005              Create-Job
     0x0006              Send-Document
     0x0007              Send-URI

     0x0008              Cancel-Job
     0x0009              Get-Job-Attributes
     0x000A              Get-Jobs
     0x000B              Get-Printer-Attributes
     0x000C-0x3FFF       reserved for future operations
     0x4000-0x8FFF       reserved for private extensions

   This allows for certain vendors to implement private extensions that
   are guaranteed to not conflict with future registered extensions.
   However, there is no guarantee that two or more private extensions
   will not conflict.

4.4.14 charset-configured (charset)

   This REQUIRED Printer attribute identifies the charset that the
   Printer object has been configured to represent 'text' and 'name'
   Printer attributes that are set by the operator, system
   administrator, or manufacturer, i.e., for "printer-name" (name),
   "printer-location" (text), "printer-info" (text), and "printer-make-
   and-model" (text).  Therefore, the value of the Printer object's
   "charset-configured" attribute MUST also be among the values of the
   Printer object's "charset-supported" attribute.

4.4.15 charset-supported (1setOf charset)

   This REQUIRED Printer attribute identifies the set of charsets that
   the Printer and contained Job objects support in attributes with
   attribute syntax 'text' and 'name'. At least the value 'utf-8' MUST
   be present, since IPP objects MUST support the UTF-8 [RFC2279]
   charset.  If a Printer object supports a charset, it means that for
   all attributes of syntax 'text' and 'name' the IPP object MUST (1)
   accept the charset in requests and return the charset in responses as
   needed.

   If more charsets than UTF-8 are supported, the IPP object MUST
   perform charset conversion between the charsets as described in
   Section 3.2.1.2.

4.4.16 natural-language-configured (naturalLanguage)

   This REQUIRED Printer attribute identifies the natural language that
   the Printer object has been configured to represent 'text' and 'name'
   Printer attributes that are set by the operator, system
   administrator, or manufacturer, i.e., for "printer-name" (name),
   "printer-location" (text), "printer-info" (text), and "printer-make-
   and-model" (text).  When returning these Printer attributes, the
   Printer object MAY return them in the configured natural language
   specified by this attribute, instead of the natural language

   requested by the client in the "attributes-natural-language"
   operation attribute.  See Section 3.1.4.1 for the specification of
   the OPTIONAL multiple natural language support.  Therefore, the value
   of the Printer object's "natural-language-configured" attribute MUST
   also be among the values of the Printer object's "generated-natural-
   language-supported" attribute.

4.4.17 generated-natural-language-supported (1setOf naturalLanguage)

   This REQUIRED Printer attribute identifies the natural language(s)
   that the Printer object and contained Job objects support in
   attributes with attribute syntax 'text' and 'name'.  The natural
   language(s) supported depends on implementation and/or configuration.
   Unlike charsets, IPP objects MUST accept requests with any natural
   language or any Natural Language Override whether the natural
   language is supported or not.

   If a Printer object supports a natural language, it means that for
   any of the attributes for which the Printer or Job object generates
   messages, i.e., for the "job-state-message" and "printer-state-
   message" attributes and Operation Messages (see Section 3.1.5) in
   operation responses, the Printer and Job objects MUST be able to
   generate messages in any of the Printer's supported natural
   languages.  See section 3.1.4 for the specification of 'text' and '
   name' attributes in operation requests and responses.

   Note: A Printer object that supports multiple natural languages,
   often has separate catalogs of messages, one for each natural
   language supported.

4.4.18 document-format-default (mimeMediaType)

   This REQUIRED Printer attribute identifies the document format that
   the Printer object has been configured to assume if the client does
   not supply a "document-format" operation attribute in any of the
   operation requests that supply document data.  The standard values
   for this attribute are Internet Media types (sometimes called MIME
   types).  For further details see the description of the '
   mimeMediaType' attribute syntax in Section 4.1.9.

4.4.19 document-format-supported (1setOf mimeMediaType)

   This REQUIRED Printer attribute identifies the set of document
   formats that the Printer object and contained Job objects can
   support. For further details see the description of the '
   mimeMediaType' attribute syntax in Section 4.1.9.

4.4.20 printer-is-accepting-jobs (boolean)

   This REQUIRED Printer attribute indicates whether the printer is
   currently able to accept jobs, i.e., is accepting Print-Job, Print-
   URI, and Create-Job requests.  If the value is 'true', the printer is
   accepting jobs.  If the value is 'false', the Printer object is
   currently rejecting any jobs submitted to it.  In this case, the
   Printer object returns the 'server-error-not-accepting-jobs' status
   code.

   Note: This value is independent of the "printer-state" and "printer-
   state-reasons" attributes because its value does not affect the
   current job; rather it affects future jobs.  This attribute may cause
   the Printer to reject jobs when the "printer-state" is 'idle' or it
   may cause the Printer object to accepts jobs when the "printer-state"
   is 'stopped'.

4.4.21 queued-job-count (integer(0:MAX))

   This RECOMMENDED Printer attribute contains a count of the number of
   jobs that are either 'pending', 'processing', 'pending-held', or '
   processing-stopped' and is set by the Printer object.

4.4.22 printer-message-from-operator (text(127))

   This Printer attribute provides a message from an operator, system
   administrator or "intelligent" process to indicate to the end user
   information or status of the printer, such as why it is unavailable
   or when it is expected to be available.

4.4.23 color-supported (boolean)

   This Printer attribute identifies whether the device is capable of
   any type of color printing at all, including highlight color.  All
   document instructions having to do with color are embedded within the
   document PDL (none are external IPP attributes in IPP/1.0).

   Note:  end-users are able to determine the nature and details of the
   color support by querying the "printer-more-info-manufacturer"
   Printer attribute.

4.4.24 reference-uri-schemes-supported (1setOf uriScheme)

   This Printer attribute specifies which URI schemes are supported for
   use in the "document-uri" operation attribute of the Print-URI or
   Send-URI operation.  If a Printer object supports these optional
   operations, it MUST support the "reference-uri-schemes-supported"
   Printer attribute with at least the following schemed URI value:

     'ftp':  The Printer object will use an FTP 'get' operation as

        defined in RFC 2228 [RFC2228] using FTP URLs as defined by
        [RFC2396] and[RFC2316].

   The Printer object MAY OPTIONALLY support other URI schemes (see
   section 4.1.6).

4.4.25 pdl-override-supported (type2 keyword)

   This REQUIRED Printer attribute expresses the ability for a
   particular Printer implementation to either attempt to override
   document data instructions with IPP attributes or not.

   This attribute takes on the following values:

     - 'attempted': This value indicates that the Printer object
       attempts to make the IPP attribute values take precedence over
       embedded instructions in the document data, however there is no
       guarantee.

     - 'not-attempted': This value indicates that the Printer object
       makes no attempt to make the IPP attribute values take precedence
       over embedded instructions in the document data.

   Section 15 contains a full description of how this attribute
   interacts with and affects other IPP attributes, especially the
   "ipp-attribute-fidelity" attribute.

4.4.26 printer-up-time (integer(1:MAX))

   This REQUIRED Printer attribute indicates the amount of time (in
   seconds) that this instance of this Printer implementation has been
   up and running.  This value is used to populate the Job attributes
   "time-at-creation", "time-at-processing", and "time-at-completed".
   These time values are all measured in seconds and all have meaning
   only relative to this attribute, "printer-up-time".  The value is a
   monotonically increasing value starting from 1 when the Printer
   object is started-up (initialized, booted, etc.).

   If the Printer object goes down at some value 'n', and comes back up,
   the implementation MAY:

     1. Know how long it has been down, and resume at some value greater
        than 'n', or
     2. Restart from 1.

   In the first case, the Printer SHOULD not tweak any existing related
   Job attributes ("time-at-creation", "time-at-processing", and "time-
   at-completed").  In the second case, the Printer object SHOULD reset

   those attributes to 0.  If a client queries a time-related Job
   attribute and finds the value to be 0, the client MUST assume that
   the Job was submitted in some life other than the Printer's current
   life.

4.4.27 printer-current-time (dateTime)

   This Printer attribute indicates the current absolute wall-clock
   time.  If an implementation supports this attribute, then a client
   could calculate the absolute wall-clock time each Job's "time-at-
   creation", "time-at-processing", and "time-at-completed" attributes
   by using both "printer-up-time" and this attribute, "printer-
   current-time".  If an implementation does not support this attribute,
   a client can only calculate the relative time of certain events based
   on the REQUIRED "printer-up-time" attribute.

4.4.28 multiple-operation-time-out (integer(1:MAX))

   This Printer attributes identifies the minimum time (in seconds) that
   the Printer object waits for additional Send-Document or Send-URI
   operations to follow a still-open multi-document Job object before
   taking  any recovery actions, such as the ones indicated in section
   3.3.1.

   It is RECOMMENDED that vendors supply a value for this attribute that
   is between 60 and 240 seconds.  An implementation MAY allow a system
   administrator to set this attribute.  If so, the system administrator
   MAY be able to set values outside this range.

4.4.29 compression-supported (1setOf type3 keyword)

   This Printer attribute identifies the set of supported compression
   algorithms for document data.  Compression only applies to the
   document data; compression does not apply to the encoding of the IPP
   operation itself.  The supported values are used to validate the
   client supplied "compression" operation attributes in Print-Job,
   Send-Document, and Send-URI requests.

   Standard values are :

     'none': no compression is used.
     'deflate':  ZIP public domain inflate/deflate) compression
        technology
     'gzip' GNU zip compression technology described in RFC 1952
        [RFC1952].
     'compress': UNIX compression technology

4.4.30 job-k-octets-supported (rangeOfInteger(0:MAX))

   This Printer attribute specifies the upper and lower bounds of total
   sizes of jobs in K octets, i.e., in units of 1024 octets. The
   supported values are used to validate the client supplied "job-k-
   octets" operation attributes in create requests.  The corresponding
   job description attribute "job-k-octets" is defined in section
   4.3.17.

   4.4.31 job-impressions-supported (rangeOfInteger(0:MAX))

   This Printer attribute specifies the upper and lower bounds for the
   number of impressions per job. The supported values are used to
   validate the client supplied "job-impressions" operation attributes
   in create requests.  The corresponding job description attribute
   "job-impressions" is defined in section 4.3.18.

4.4.32 job-media-sheets-supported (rangeOfInteger(0:MAX))

   This Printer attribute specifies the upper and lower bounds for the
   number of media sheets per job. The supported values are used to
   validate the client supplied "job-media-sheets" operation attributes
   in create requests.  The corresponding Job attribute "job-media-
   sheets" is defined in section 4.3.19.

5. Conformance

   This section describes conformance issues and requirements. This
   document introduces model entities such as objects, operations,
   attributes, attribute syntaxes, and attribute values.  These
   conformance sections describe the conformance requirements which
   apply to these model entities.

5.1 Client Conformance Requirements

   A conforming client MUST support all REQUIRED operations as defined
   in this document.  For each attribute included in an operation
   request, a conforming client MUST supply a value whose type and value
   syntax conforms to the requirements of the Model document as
   specified in Sections 3 and 4.  A conforming client MAY supply any
   registered extensions and/or private extensions in an operation
   request, as long as they meet the requirements in Section 6.

   Otherwise, there are no conformance requirements placed on the user
   interfaces provided by IPP clients or their applications.  For
   example, one application might not allow an end user to submit
   multiple documents per job, while another does.  One application
   might first query a Printer object in order to supply a graphical
   user interface (GUI) dialogue box with supported and default values
   whereas a different implementation might not.

   When sending a request, an IPP client NEED NOT supply any attributes
   that are indicated as OPTIONALLY supplied by the client.

   A client MUST be able to accept any of the attribute syntaxes defined
   in Section 4.1, including their full range, that may be returned to
   it in a response from a Printer object.  In particular for each
   attribute that the client supports whose attribute syntax is 'text',
   the client MUST accept and process both the 'textWithoutLanguage' and
   'textWithLanguage' forms.  Similarly, for each attribute that the
   client supports whose attribute syntax is 'name', the client MUST
   accept and process both the 'nameWithoutLanguage' and '
   nameWithLanguage' forms.  For presentation purposes, truncation of
   long attribute values is not recommended.  A recommended approach
   would be for the client implementation to allow the user to scroll
   through long attribute values.

   A query response may contain attribute groups, attributes, and values
   that the client does not expect.  Therefore, a client implementation
   MUST gracefully handle such responses and not refuse to inter-operate
   with a conforming Printer that is returning extended registered or
   private attributes and/or attribute values that conform to Section 6.
   Clients may choose to ignore any parameters, attributes, or values
   that they do not understand.

5.2 IPP Object Conformance Requirements

   This section specifies the conformance requirements for conforming
   implementations with respect to objects, operations, and attributes.

5.2.1 Objects

   Conforming implementations MUST implement all of the model objects as
   defined in this specification in the indicated sections:

     Section 2.1 - Printer Object
     Section 2.2 - Job Object

5.2.2 Operations

   Conforming IPP object implementations MUST implement all of the
   REQUIRED model operations, including REQUIRED responses, as defined
   in this specification in the indicated sections:

     For a Printer object:
        Print-Job (section 3.2.1)          REQUIRED
        Print-URI (section 3.2.2)          OPTIONAL
        Validate-Job (section 3.2.3)       REQUIRED
        Create-Job (section 3.2.4)         OPTIONAL

        Get-Printer-Attributes (section 3.2.5)  REQUIRED
        Get-Jobs (section 3.2.6)           REQUIRED

     For a Job object:
        Send-Document (section 3.3.1)      OPTIONAL
        Send-URI (section 3.3.2)           OPTIONAL
        Cancel-Job (section 3.3.3)         REQUIRED
        Get-Job-Attributes (section 3.3.4) REQUIRED

   Conforming IPP objects MUST support all REQUIRED operation attributes
   and all values of such attributes if so indicated in the description.
   Conforming IPP objects MUST ignore all unsupported or unknown
   operation attributes or operation attribute groups received in a
   request, but MUST reject a request that contains a supported
   operation attribute that contains an unsupported value.

   The following section on object attributes specifies the support
   required for object attributes.

5.2.3 IPP Object Attributes

   Conforming IPP objects MUST support all of the REQUIRED object
   attributes, as defined in this specification in the indicated
   sections.

   If an object supports an attribute, it MUST support only those values
   specified in this document or through the extension mechanism
   described in section 5.2.4. It MAY support any non-empty subset of
   these values.  That is, it MUST support at least one of the specified
   values and at most all of them.

5.2.4 Extensions

   A conforming IPP object MAY support registered extensions and private
   extensions, as long as they meet the requirements specified in
   Section 6.

   For each attribute included in an operation response, a conforming
   IPP object MUST return a value whose type and value syntax conforms
   to the requirement of the Model document as specified in Sections 3
   and 4.

5.2.5 Attribute Syntaxes

   An IPP object MUST be able to accept any of the attribute syntaxes
   defined in Section 4.1, including their full range, in any operation
   in which a client may supply attributes or the system administrator
   may configure attributes (by means outside the scope of IPP/1.0).  In
   particular for each attribute that the IPP object supports whose
   attribute syntax is 'text', the IPP object MUST accept and process
   both the 'textWithoutLanguage' and 'textWithLanguage' forms.
   Similarly, for each attribute that the IPP object supports whose
   attribute syntax is 'name', the IPP object MUST accept and process
   both the 'nameWithoutLanguage' and 'nameWithLanguage' forms.
   Furthermore, an IPP object MUST return attributes to the client in
   operation responses that conform to the syntax specified in Section
   4.1, including their full range if supplied previously by a client.

5.3 Charset and Natural Language Requirements

   All clients and IPP objects MUST support the 'utf-8' charset as
   defined in section 4.1.7.

   IPP objects MUST be able to accept any client request which correctly
   uses the "attributes-natural-language" operation attribute or the
   Natural Language Override mechanism on any individual attribute
   whether or not the natural language is supported by the IPP object.
   If an IPP object supports a natural language, then it MUST be able to
   translate (perhaps by table lookup) all generated 'text' or 'name'
   attribute values into one of the supported languages (see section
   3.1.4).  That is, the IPP object that supports a natural language
   NEED NOT be a general purpose translator of any arbitrary 'text' or '
   name' value supplied by the client into that natural language.
   However, the object MUST be able to translate (automatically
   generate) any of its own attribute values and messages into that
   natural language.

5.4 Security Conformance Requirements

   Conforming IPP Printer objects MAY support Secure Socket Layer
   Version 3 (SSL3) [SSL] access, support access without SSL3 or support
   both means of access.

   Conforming IPP clients SHOULD support SSL3 access and non-SSL3
   access.  Note: This client requirement to support both means that
   conforming IPP clients will be able to inter-operate with any IPP
   Printer object.

   For a detailed discussion of security considerations and the IPP
   application security profile required for SSL3 support, see section
   8.

6. IANA Considerations (registered and private extensions)

   This section describes how IPP can be extended to allow the following
   registered and private extensions to IPP:

     1. keyword attribute values
     2. enum attribute values
     3. attributes
     4. attribute syntaxes
     5. operations
     6. attribute groups
     7. status codes

   Extensions registered for use with IPP/1.0 are OPTIONAL for client
   and IPP object conformance to the IPP/1.0 Model specification.

   These extension procedures are aligned with the guidelines as set
   forth by the IESG [RFC2434].  Section 11 describes how to propose new
   registrations for consideration.  IANA will reject registration
   proposals that leave out required information or do not follow the
   appropriate format described in Section 11.  IPP/1.0 may also be
   extended by an appropriate RFC that specifies any of the above
   extensions.

6.1 Typed 'keyword' and 'enum' Extensions

   IPP allows for 'keyword' and 'enum' extensions (see sections 4.1.2.3
   and 4.1.4).  This document uses prefixes to the 'keyword' and 'enum'
   basic attribute syntax type in order to communicate extra information
   to the reader through its name. This extra information is not
   represented in the protocol because it is unimportant to a client or
   Printer object.  The list below describes the prefixes and their
   meaning.

     "type1":  The IPP specification must be revised to add a new
        keyword or a new enum.  No private keywords or enums are
        allowed.

     "type2":  Implementers can, at any time, add new keyword or enum
        values by proposing the complete specification to IANA:

        iana@iana.org

        IANA will forward the registration proposal to the IPP
        Designated Expert who will review the proposal with a mailing
        list that the Designated Expert keeps for this purpose.
        Initially, that list will be the mailing list used by the IPP
        WG:

             ipp@pwg.org

        even after the IPP WG is disbanded as permitted by [RFC2434].
        The IPP Designated Expert is appointed by the IESG Area Director
        responsible for IPP, according to [RFC2434].

        When a type2 keyword or enum is approved, the IPP Designated
        Expert becomes the point of contact for any future maintenance
        that might be required for that registration.

     "type3":  Implementers can, at any time, add new keyword and enum
        values by submitting the complete specification to IANA as for
        type2 who will forward the proposal to the IPP Designated
        Expert.  While no additional technical review is required, the
        IPP Designated Expert may, at his/her discretion, forward the
        proposal to the same mailing list as for type2 registrations for
        advice and comment.

        When a type3 keyword or enum is approved by the IPP Designated
        Expert, the original proposer becomes the point of contact for
        any future maintenance that might be required for that
        registration.

   For type2 and type3 keywords, the proposer includes the name of the
   keyword in the registration proposal and the name is part of the
   technical review.

   After type2 and type3 enums specifications are approved, the IPP
   Designated Expert in consultation with IANA assigns the next
   available enum number for each enum value.

   IANA will publish approved type2 and type3 keyword and enum
   attributes value registration specifications in:

        ftp.isi.edu/iana/assignments/ipp/attribute-values/xxx/yyy.txt

   where xxx is the attribute name that specifies the initial values and
   yyy.txt is a descriptive file name that contains one or more enums or
   keywords approved at the same time.  For example, if several
   additional enums for stapling are approved for use with the

   "finishings" attribute (and "finishings-default" and "finishings-
   supported" attributes), IANA will publish the additional values in
   the file:

        ftp.isi.edu/iana/assignments/ipp/attribute-
        values/finishings/stapling.txt

   Note: Some attributes are defined to be: 'type3 keywords' | 'name'
   which allows for attribute values to be extended by a site
   administrator with administrator defined names.  Such names are not
   registered with IANA.

   By definition, each of the three types above assert some sort of
   registry or review process in order for extensions to be considered
   valid.  Each higher numbered level (1, 2, 3) tends to be decreasingly
   less stringent than the previous level.   Therefore, any typeN value
   MAY be registered using a process for some typeM where M is less than
   N, however such registration is NOT REQUIRED.  For example, a type3
   value MAY be registered in a type 1 manner (by being included in a
   future version of an IPP specification), however, it is NOT REQUIRED.

   This specification defines keyword and enum values for all of the
   above types, including type3 keywords.

   For private (unregistered) keyword extensions, implementers SHOULD
   use keywords with a suitable distinguishing prefix, such as "xxx-"
   where xxx is the (lowercase) fully qualified company name registered
   with IANA for use in domain names [RFC1035].  For example, if the
   company XYZ Corp.  had obtained the domain name "XYZ.com", then a
   private keyword 'abc' would be: 'xyz.com-abc'.

   Note: RFC 1035 [RFC1035] indicates that while upper and lower case
   letters are allowed in domain names, no significance is attached to
   the case.  That is, two names with the same spelling but different
   case are to be treated as if identical.  Also, the labels in a domain
   name must follow the rules for ARPANET host names:  They must start
   with a letter, end with a letter or digit, and have as interior
   characters only letters, digits, and hyphen.  Labels must be 63
   characters or less.  Labels are separated by the "." character.

   For private (unregistered) enum extension, implementers MUST use
   values in the reserved integer range which is 2**30 to 2**31-1.

6.2 Attribute Extensibility

   Attribute names are type2 keywords.  Therefore, new attributes may be
   registered and have the same status as attributes in this document by
   following the type2 extension rules.  For private (unregistered)
   attribute extensions, implementers SHOULD use keywords with a
   suitable distinguishing prefix as described in Section 6.1.

   IANA will publish approved attribute registration specifications as
   separate files:

        ftp.isi.edu/iana/assignments/ipp/attributes/xxx-yyy.txt

   where "xxx-yyy" is the new attribute name.

   If a new Printer object attribute is defined and its values can be
   affected by a specific document format, its specification needs to
   contain the following sentence:

     "The value of this attribute returned in a Get-Printer-Attributes
     response MAY depend on the "document-format" attribute supplied
     (see Section 3.2.5.1)."

   If the specification does not, then its value in the Get-Printer-
   Attributes response MUST NOT depend on the "document-format" supplied
   in the request.  When a new Job Template attribute is registered, the
   value of the Printer attributes MAY vary with "document-format"
   supplied in the request without the specification having to indicate
   so.

6.3 Attribute Syntax Extensibility

   Attribute syntaxes are like type2 enums.  Therefore, new attribute
   syntaxes may be registered and have the same status as attribute
   syntaxes in this document by following the type2 extension rules
   described in Section 6.1.  The value codes that identify each of the
   attribute syntaxes are assigned in the Encoding and Transport
   specification [RFC2565], including a designated range for private,
   experimental use.

   For attribute syntaxes, the IPP Designated Expert in consultation
   with IANA assigns the next attribute syntax code in the appropriate
   range as specified in [RFC2565].  IANA will publish approved
   attribute syntax registration specifications as separate files:

        ftp.isi.edu/iana/assignments/ipp/attribute-syntaxes/xxx-yyy.txt

   where 'xxx-yyy' is the new attribute syntax name.

6.4 Operation Extensibility

   Operations may also be registered following the type2 procedures
   described in Section 6.1, though major new operations will usually be
   done by a new standards track RFC that augments this document.  For
   private (unregistered) operation extensions, implementers MUST use
   the range for the "operation-id" in requests specified in Section
   4.4.13 "operations-supported" Printer attribute.

   For operations, the IPP Designated Expert in consultation with IANA
   assigns the next operation-id code as specified in Section 4.4.13.
   IANA will publish approved operation registration specifications as
   separate files:

        ftp.isi.edu/iana/assignments/ipp/operations/Xxx-Yyy.txt

   where "Xxx-Yyy" is the new operation name.

6.5 Attribute Groups

   Attribute groups passed in requests and responses may be registered
   following the type2 procedures described in Section 6.1.  The tags
   that identify each of the attribute groups are assigned in [RFC2565].

   For attribute groups, the IPP Designated Expert in consultation with
   IANA assigns the next attribute group tag code in the appropriate
   range as specified in [RFC2565].  IANA will publish approved
   attribute group registration specifications as separate files:

        ftp.isi.edu/iana/assignments/ipp/attribute-group-tags/xxx-yyy-
        tag.txt

   where 'xxx-yyy-tag' is the new attribute group tag name.

6.6 Status Code Extensibility

   Operation status codes may also be registered following the type2
   procedures described in Section 6.1.  The values for status codes are
   allocated in ranges as specified in Section 13 for each status code
   class:

     "informational" - Request received, continuing process
     "successful" - The action was successfully received, understood,
        and accepted
     "redirection" - Further action must be taken in order to complete
        the request
     "client-error" - The request contains bad syntax or cannot be
        fulfilled

     "server-error" - The IPP object  failed to fulfill an apparently
        valid request

   For private (unregistered) operation status code extensions,
   implementers MUST use the top of each range as specified in Section
   13.

   For operation status codes, the IPP Designated Expert in consultation
   with IANA assigns the next status code in the appropriate class range
   as specified in Section 13.  IANA will publish approved status code
   registration specifications as separate files:

        ftp.isi.edu/iana/assignments/ipp/status-codes/xxx-yyy.txt

   where "xxx-yyy" is the new operation status code keyword.

6.7 Registration of MIME types/sub-types for document-formats

   The "document-format" attribute's syntax is 'mimeMediaType'.  This
   means that valid values are Internet Media Types (see Section 4.1.9).
   RFC 2045 [RFC2045] defines the syntax for valid Internet media types.
   IANA is the registry for all Internet media types.

6.8 Registration of charsets for use in 'charset' attribute values

   The "attributes-charset" attribute's syntax is 'charset'.  This means
   that valid values are charsets names.  When a charset in the IANA
   registry has more than one name (alias), the name labeled as
   "(preferred MIME name)", if present, MUST be used (see Section
   4.1.7).  IANA is the registry for charsets following the procedures
   of [RFC2278].

7. Internationalization Considerations

   Some of the attributes have values that are text strings and names
   which are intended for human understanding rather than machine
   understanding (see the 'text' and 'name' attribute syntaxes in
   Sections 4.1.1 and 4.1.2).

   In each operation request, the client

     - identifies the charset and natural language of the request which
       affects each supplied 'text' and 'name' attribute value, and
     - requests the charset and natural language for attributes returned
       by the IPP object in operation responses (as described in Section
       3.1.4.1).

   In addition, the client MAY separately and individually identify the
   Natural Language Override of a supplied 'text' or 'name' attribute
   using the 'textWithLanguage' and 'nameWithLanguage' technique
   described section 4.1.1.2 and 4.1.2.2 respectively.

   All IPP objects MUST support the UTF-8 [RFC2279] charset in all '
   text' and 'name' attributes supported.  If an IPP object supports
   more than the UTF-8 charset, the object MUST convert between them in
   order to return the requested charset to the client according to
   Section 3.1.4.2.  If an IPP object supports more than one natural
   language, the object SHOULD return 'text' and 'name' values in the
   natural language requested where those values are generated by the
   Printer (see Section 3.1.4.1).

   For Printers that support multiple charsets and/or multiple natural
   languages in 'text' and 'name' attributes, different jobs may have
   been submitted in differing charsets and/or natural languages.  All
   responses MUST be returned in the charset requested by the client.
   However, the Get-Jobs operation uses the 'textWithLanguage' and '
   nameWithLanguage' mechanism to identify the differing natural
   languages with each job attribute returned.

   The Printer object also has configured charset and natural language
   attributes.   The client can query the Printer object to determine
   the list of charsets and natural languages supported by the Printer
   object and what the Printer object's configured values are.  See the
   "charset-configured", "charset-supported", "natural-language-
   configured", and "generated-natural-language-supported" Printer
   description attributes for more details.

   The "charset-supported" attributed identifies the supported charsets.
   If a charset is supported, the IPP object MUST be capable of
   converting to and from that charset into any other supported charset.
   In many cases, an IPP object will support only one charset and it
   MUST be the UTF-8 charset.

   The "charset-configured" attribute identifies the one supported
   charset which is the native charset given the current configuration
   of the IPP object (administrator defined).

   The "generated-natural-language-supported" attribute identifies the
   set of supported natural languages for generated messages; it is not
   related to the set of natural languages that must be accepted for
   client supplied 'text' and 'name' attributes.  For client supplied '
   text' and 'name' attributes, an IPP object MUST accept ALL supplied
   natural languages.  Just because a Printer object is currently

   configured to support 'en-us' natural language does not mean that the
   Printer object should reject a job if the client supplies a job name
   that is in 'fr-ca'.

   The "natural-language-configured" attribute identifies the one
   supported natural language for generated messages which is the native
   natural language given the current configuration of the IPP object
   (administrator defined).

   Attributes of type 'text' and 'name' are populated from different
   sources.  These attributes can be categorized into following groups
   (depending on the source of the attribute):

     1. Some attributes are supplied by the client (e.g., the client
        supplied "job-name", "document-name", and "requesting-user-name"
        operation attributes along with the corresponding Job object's
        "job-name" and "job-originating-user-name" attributes).  The IPP
        object MUST accept these attributes in any natural language no
        matter what the set of supported languages for generated
        messages
     2. Some attributes are supplied by the system administrator (e.g.,
        the Printer object's "printer-name" and "printer-location"
        attributes).  These too can be in any natural language.  If the
        natural language for these attributes is different than what a
        client requests, then they must be reported using the Natural
        Language Override mechanism.
     3. Some attributes are supplied by the device manufacturer (e.g.,
        the Printer object's "printer-make-and-model" attribute).  These
        too can be in any natural language.  If the natural language for
        these attributes is different than what a client requests, then
        they must be reported using the Natural Language Override
        mechanism.
     4. Some attributes are supplied by the operator (e.g., the Job
        object's "job-message-from-operator" attribute). These too can
        be in any natural language.  If the natural language for these
        attributes is different than what a client requests, then they
        must be reported using the Natural Language Override mechanism.
     5. Some attributes are generated by the IPP object (e.g., the Job
        object's "job-state-message" attribute, the Printer object's
        "printer-state-message" attribute, and the "status-message"
        operation attribute).  These attributes can only be in one of
        the "generated-natural-language-supported" natural languages.
        If a client requests some natural language for these attributes
        other than one of the supported values, the IPP object SHOULD
        respond using the value of the "natural-language-configured"
        attribute (using the Natural Language Override mechanism if
        needed).

   The 'text' and 'name' attributes specified in this version of this
   document (additional ones will be registered according to the
   procedures in Section 6) are:

     Attributes                      Source
     --------------------------      ----------
     Operation Attributes
        job-name (name)               client
        document-name (name)          client
        requesting-user-name (name)   client
        status-message                Job or Printer object

     Job Template Attributes:
        job-hold-until)          client matches administrator-configured
            (keyword | name
        job-hold-until-default   client matches administrator-configured
            (keyword | name)
        job-hold-until-supported client matches administrator-configured
            (keyword | name)
        job-sheets               client matches administrator-configured
            (keyword | name)
        job-sheets-default       client matches administrator-configured
            (keyword | name)
        job-sheets-supported     client matches administrator-configured
            (keyword | name)
        media                    client matches administrator-configured
            (keyword | name)
        media-default            client matches administrator-configured
            (keyword | name)
        media-supported          client matches administrator-configured
            (keyword | name)
        media-ready              client matches administrator-configured
            (keyword | name)

     Job Description Attributes:
        job-name (name)               client or Printer object
        job-originating-user-name (name)   Printer object
        job-state-message (text)      Job or Printer object
        output-device-assigned (name(127)) administrator
        job-message-from-operator (text(127))   operator

     Printer Description Attributes:
        printer-name (name(127))      administrator
        printer-location (text(127))  administrator
        printer-info (text(127))      administrator
        printer-make-and-model (text(127)) administrator or manufacturer
        printer-state-message (text)  Printer object
        printer-message-from-operator (text(127))    operator

8. Security Considerations

   Some IPP objects MAY be deployed over protocol stacks that support
   Secure Socket Layer Version 3 (SSL3) [SSL].  Note:  SSL3 is not an
   IETF standards track specification.  Other IPP objects MAY be
   deployed over protocol stacks that do not support SSL3.  Some IPP
   objects MAY be deployed over both types of protocol stacks.  Those
   IPP objects that support SSL3, are capable of supporting mutual
   authentication as well as privacy of messages via multiple encryption
   schemes.  An important point about security related information for
   SSL3 access to an IPP object, is that the security-related parameters
   (authentication, encryption keys, etc.) are "out-of-band" to the
   actual IPP protocol.

   An IPP object that does not support SSL3 MAY elect to support a
   transport layer that provides other security mechanisms.  For
   example, in a mapping of IPP over HTTP/1.1 [RFC2565], if the IPP
   object does not support SSL3, HTTP still allows for client
   authentication using Digest Access Authentication (DAA) [RFC2069].

   It is difficult to anticipate the security risks that might exist in
   any given IPP environment. For example, if IPP is used within a given
   corporation over a private network, the risks of exposing document
   data may be low enough that the corporation will choose not to use
   encryption on that data.  However, if the connection between the
   client and the IPP object is over a public network, the client may
   wish to protect the content of the information during transmission
   through the network with encryption.

   Furthermore, the value of the information being printed may vary from
   one IPP environment to the next. Printing payroll checks, for
   example, would have a different value than printing public
   information from a file.  There is also the possibly of denial-of-
   service attacks, but denial-of-service attacks against printing
   resources are not well understood and there is no published
   precedents regarding this scenario.

   Once the authenticated identity of the requester has been supplied to
   the IPP object, the object uses that identity to enforce any
   authorization policy that might be in place.  For example, one site's
   policy might be that only the job owner is allowed to cancel a job.
   The details and mechanisms to set up a particular access control
   policy are not part of IPP/1.0, and must be established via some
   other type of administrative or access control framework.  However,
   there are operation status codes that allow an IPP server to return
   information back to a client about any potential access control
   violations for an IPP object.

   During a create operation, the client's identity is recorded in the
   Job object in an implementation-defined attribute.  This information
   can be used to verify a client's identity for subsequent operations
   on that Job object in order to enforce any access control policy that
   might be in effect.  See section 8.3 below for more details.

   Since the security levels or the specific threats that any given IPP
   system administrator may be concerned with cannot be anticipated, IPP
   MUST be capable of operating with different security mechanisms and
   security policies as required by the individual installation.
   Security policies might vary from very strong, to very weak, to none
   at all, and corresponding security mechanisms will be required. SSL3
   supports the type of negotiated levels of security required by most,
   if not all, potential IPP environments. IPP environments that require
   no security can elect to deploy IPP objects that do not utilize the
   optional SSL3 security mechanisms.

8.1 Security Scenarios

   The following sections describe specific security attacks for IPP
   environments.  Where examples are provided they should be considered
   illustrative of the environment and not an exhaustive set. Not all of
   these environments will necessarily be addressed in initial
   implementations of IPP.

8.1.1 Client and Server in the Same Security Domain

   This environment is typical of internal networks where traditional
   office workers print the output of personal productivity applications
   on shared work-group printers, or where batch applications print
   their output on large production printers. Although the identity of
   the user may be trusted in this environment, a user might want to
   protect the content of a document against such attacks as
   eavesdropping, replaying or tampering.

8.1.2 Client and Server in Different Security Domains

   Examples of this environment include printing a document created by
   the client on a publicly available printer, such as at a commercial
   print shop; or printing a document remotely on a business associate's
   printer.  This latter operation is functionally equivalent to sending
   the document to the business associate as a facsimile. Printing
   sensitive information on a Printer in a different security domain
   requires strong security measures. In this environment authentication
   of the printer is required as well as protection against unauthorized
   use of print resources. Since the document crosses security domains,

   protection against eavesdropping and document tampering are also
   required. It will also be important in this environment to protect
   Printers against "spamming" and malicious document content.

8.1.3 Print by Reference

   When the document is not stored on the client, printing can be done
   by reference. That is, the print request can contain a reference, or
   pointer, to the document instead of the actual document itself.
   Standard methods currently do not exist for remote entities to
   "assume" the credentials of a client for forwarding requests to a 3rd
   party. It is anticipated that Print-By-Reference will be used to
   access "public" documents and that sophisticated methods for
   authenticating "proxies" will not be specified for version 1 of IPP.

8.2 URIs for SSL3 and non-SSL3 Access

   As described earlier, an IPP object can support SSL3 access, non-SSL3
   access, or both.  The "printer-uri-supported" attribute contains the
   Printer object's URI(s).  Its companion attribute, "uri-security-
   supported", identifies the security mechanism used for each URI
   listed in the "printer-uri-supported" attribute.  For each Printer
   operation request, a client MUST supply only one URI in the
   "printer-uri" operation attribute.  In other words, even though the
   Printer supports more than one URI, the client only interacts with
   the Printer object using one if its URIs.  This duality is not needed
   for Job objects, since the Printer objects is the factory for Job
   objects, and the Printer object will generate the correct URI for new
   Job objects depending on the Printer object's security configuration.

8.3 The "requesting-user-name" (name(MAX)) Operation Attribute

   Each operation MUST specify the user who is performing the operation
   in both of the following two ways:

     1) via the REQUIRED "requesting-user-name" operation attribute that
        a client SHOULD supply in all operations. The client MUST obtain
        the value for this attribute from an environmental or network
        login name for the user, rather than allowing the user to supply
        any value. If the client does not supply a value for
        "requesting-user-name", the printer MUST assume that the client
        is supplying some anonymous name, such as "anonymous".
     2) via an authentication mechanism of the underlying transport
        which may be configured to give no authentication information.

   There are six cases to consider:

     a) the authentication mechanism gives no information, and the
        client doesn't specify  "requesting-user-name".
     b) the authentication mechanism gives no information, but the
        client specifies "requesting-user-name".
     c) the authentication mechanism specifies a user which has no human
        readable representation, and the client doesn't specify
        "requesting-user-name".
     d) the authentication mechanism specifies a user which has no human
        readable representation, but the client specifies "requesting-
        user-name".
     e) the authentication mechanism specifies a user which has a human
        readable representation. The Printer object ignores the
        "requesting-user-name".
     f) the authentication mechanism specifies a user who is trusted and
        whose name means that the value of the "requesting-user-name",
        which MUST be present, is treated as the authenticated name.

   Note:  Case "f" is intended for a tightly coupled gateway and server
   to work together so that the "user" name is able to be that of the
   gateway client and not that of the gateway.  Because most, if not
   all, system vendors will initially implement IPP via a gateway into
   their existing print system, this mechanism is necessary unless the
   authentication mechanism allows a gateway (client) to act on behalf
   of some other client.

   The user-name has two forms:

     - one that is human readable: it is held in the REQUIRED "job-
       originating-user-name" Job Description attribute which is set
       during the job creation operations. It is used for presentation
       only, such as returning in queries or printing on start sheets
     - one for authorization: it is held in an undefined (by IPP) Job
       object attribute which is set by the job creation operation.  It
       is used to authorize other operations, such as Send-Document,
       Send-URI, Cancel-Job, to determine the user when the "my-jobs"
       attribute is specified with Get-Jobs, and to limit what
       attributes and values to return with Get-Job-Attributes and Get-
       Jobs.

   The human readable user name:

     - is the value of the "requesting-user-name" for cases b, d and f.
     - comes from the authentication mechanism for case e
     - is some anonymous name, such as "anonymous" for cases a and c.

   The user name used for authorization:

     - is the value of the "requesting-user-name" for cases b  and f.
     - comes from the authentication mechanism for cases c, d and  e
     - is some anonymous name, such as "anonymous" for case a.

   The essence of these rules for resolving conflicting sources of
   user-names is that a printer implementation is free to pick either
   source as long as it achieves consistent results.  That is, if a user
   uses the same path for a series of requests, the requests MUST appear
   to come from the same user from the standpoint of both the human-
   readable user name and the user name for authorization.  This rule
   MUST continue to apply even if a request could be authenticated by
   two or more mechanisms.  It doesn't matter which of  several
   authentication mechanisms a Printer uses as long as it achieves
   consistent results.  If a client uses more than one authentication
   mechanism, it is recommended that an administrator make all
   credentials resolve to the same user and user-name as much as
   possible.

8.4 Restricted Queries

   In many IPP operations, a client supplies a list of attributes to be
   returned in the response.  For security reasons, an IPP object may be
   configured not to return all attributes (or all values) that a client
   requests.  The job attributes returned MAY depend on whether the
   requesting user is the same as the user that submitted the job. The
   IPP object MAY even return none of the requested attributes. In such
   cases, the status returned is the same as if the object had returned
   all requested attributes.  The client cannot tell by such a response
   whether the requested attribute was present or absent on the object.

8.5 Queries on jobs submitted using non-IPP protocols

   If the device that an IPP Printer is representing is able to accept
   jobs using other job submission protocols in addition to IPP, it is
   RECOMMENDED that such an implementation at least allow such "foreign"
   jobs to be queried using Get-Jobs returning "job-id" and "job-uri" as
   'unknown'.  Such an implementation NEED NOT support all of the same
   IPP job attributes as for IPP jobs.  The IPP object returns the '
   unknown' out-of-band value for any requested attribute of a foreign
   job that is supported for IPP jobs, but not for foreign jobs.

   It is further RECOMMENDED, that the IPP Printer generate "job-id" and
   "job-uri" values for such "foreign jobs", if possible, so that they
   may be targets of other IPP operations, such as Get-Job-Attributes
   and Cancel-Job.  Such an implementation also needs to deal with the
   problem of authentication of such foreign jobs.  One approach would
   be to treat all such foreign jobs as belonging to users other than
   the user of the IPP client.  Another approach would be for the

   foreign job to belong to 'anonymous'.  Only if the IPP client has
   been authenticated as an operator or administrator of the IPP Printer
   object, could the foreign jobs be queried by an IPP request.
   Alternatively, if the security policy is to allow users to query
   other users' jobs, then the foreign jobs would also be visible to an
   end-user IPP client using Get-Jobs and Get-Job-Attributes.

8.6 IPP Security Application Profile for SSL3

   The IPP application profile for SSL3 follows the "Secure Socket
   Layer" requirement as documented in the SSL3 specification [SSL].
   For interoperability, the SSL3 cipher suites are:

        SSL_RSA_WITH_RC4_128_MD5
        SSL_RSA_WITH_3DES_EDE_CBC_SHA
        SSL_RSA_WITH_DES_CBC_SHA
        SSL_RSA_EXPORT_WITH_RC4_40_MD5
        SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5
        SSL_RSA_WITH_NULL_MD5

   Client implementations MUST NOT assume any other cipher suites are
   supported by an IPP Printer object.

   If a conforming IPP object supports SSL3, it MUST implement and
   support the cipher suites listed above and MAY support additional
   cipher suites.

   A conforming IPP client SHOULD support SSL3 including the cipher
   suites listed above.  A conforming IPP client MAY support additional
   cipher suites.

   It is possible that due to certain government export restrictions
   some non-compliant versions of this extension could be deployed.
   Implementations wishing to inter-operate with such non-compliant
   versions MAY offer the SSL_RSA_EXPORT_WITH_RC4_40_MD5 and
   SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5 mechanisms.  However, since 40 bit
   ciphers are known to be vulnerable to attack by current technology,
   any client which actives a 40 bit cipher MUST NOT indicate to the
   user that the connection is completely secure from eavesdropping.

9. References

   [ASCII]      Coded Character Set - 7-bit American Standard Code for
                Information Interchange (ASCII), ANSI X3.4-1986. This
                standard is the specification of the US-ASCII charset.

   [HTPP]       J. Barnett, K. Carter, R. DeBry,  "Initial Draft -
                Hypertext Printing Protocol - HTPP/1.0", October 1996.
                ftp://ftp.pwg.org/pub/pwg/ipp/historic/htpp/
                overview.ps.gz

   [IANA-CS]    IANA Registry of Coded Character Sets:
                ftp://ftp.isi.edu/in-notes/iana/assignments/character-
                sets

   [IANA-MT]    IANA Registry of Media Types:  ftp://ftp.isi.edu/in-
                notes/iana/assignments/media-types/

   [ipp-iig]    Hastings, T. and C. Manros, "Internet Printing
                Protocol/1.0:  Implementer's Guide", Work in Progress.

   [ISO10646-1] ISO/IEC 10646-1:1993, "Information technology --
                Universal Multiple-Octet Coded Character Set (UCS) -
                Part 1: Architecture and Basic Multilingual Plane,
                JTC1/SC2."

   [ISO8859-1]  ISO/IEC 8859-1:1987, "Information technology -- 8-bit
                One-Byte Coded Character Set - Part 1: Latin Alphabet Nr
                1", 1987, JTC1/SC2.

   [ISO10175]   ISO/IEC 10175 Document Printing Application (DPA), June
                1996.

   [LDPA] T. Hastings, S. Isaacson, M. MacKay, C. Manros, D. Taylor, P.
                Zehler, "LDPA - Lightweight Document Printing
                Application", October 1996,
                ftp://ftp.pwg.org/pub/pwg/ipp/historic/ldpa/ldpa8.pdf.gz

   [P1387.4]    Kirk, M. (Editor), POSIX System Administration - Part 4:
                Printing Interfaces, POSIX 1387.4 D8, 1994.

   [PSIS]       Herriot, R. (editor), X/Open A Printing System
                Interoperability Specification (PSIS), August 1995.

   [PWG]        Printer Working Group, http://www.pwg.org.

   [RFC1035]    Mockapetris, P., "DOMAIN NAMES - IMPLEMENTATION AND
                SPECIFICATION", STD 13, RFC 1035, November 1987.

   [RFC1759]    Smith, R., Wright, F., Hastings, T., Zilles, S. and J.
                Gyllenskog, "Printer MIB", RFC 1759, March 1995.

   [RFC1766]    Alvestrand, H., "Tags for the Identification of
                Languages", RFC 1766, March 1995.

   [RFC1179]    McLaughlin, L. (Editor), "Line Printer Daemon Protocol",
                RFC 1179, August 1990.

   [RFC1952]    Deutsch, P., "GZIP file format specification version
                4.3", RFC 1952, May 1996.

   [RFC2045]    Freed, N. and N. Borenstein, " Multipurpose Internet
                Mail Extensions (MIME) Part One: Format of Internet
                Message Bodies", RFC 2045, November 1996.

   [RFC2046]    Freed, N. and N. Borenstein, "Multipurpose Internet Mail
                Extensions (MIME) Part Two: Media Types", RFC 2046,
                November 1996.

   [RFC2048]    Freed, N., Klensin, J. and J. Postel, "Multipurpose
                Internet Mail Extension (MIME) Part Four: Registration
                Procedures", RFC 2048, November 1996.

   [RFC2068]    Fielding, R., Gettys, J., Mogul, J., Frystyk, H. AND T.
                Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1",
                RFC 2068, January 1997.

   [RFC2069]    Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P.,
                Luotonen, A., Sink, E. and L. Stewart, "An Extension to
                HTTP: Digest Access Authentication", RFC 2069, January
                1997.

   [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2228]    Horowitz, M. and S. Lunt, "FTP Security Extensions", RFC
                2228, October 1997.

   [RFC2277]    Alvestrand, H., "IETF Policy on Character Sets and
                Languages" RFC 2277, January 1998.

   [RFC2278]    Freed, N. and J. Postel:  "IANA Charset Registration
                Procedures", BCP 19, RFC 2278, January 1998.

   [RFC2279]    Yergeau, F., "UTF-8, a transformation format of ISO
                10646", RFC 2279, January 1998.

   [RFC2316]    Bellovin, S., "Report of the IAB Security Architecture
                Workshop", RFC 2316, April 1998.

   [RFC2396]    Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
                Resource Identifiers (URI): Generic Syntax", RFC 2396,
                August 1998.

   [RFC2434]    Narten, T. and H. Alvestrand, "Guidelines for Writing an
                IANA Considerations Section in RFCs", BCP 26, RFC 2434,
                October 1998.

   [RFC2565]    Herriot, R., Butler, S., Moore, P. and R. Tuner
                "Internet Printing Protocol/1.0: Encoding and
                Transport", RFC 2565, April 1999.

   [RFC2567]    Wright, D.,  "Design Goals for an Internet Printing
                Protocol", RFC 2567, April 1999.

   [RFC2568]    Zilles, S., "Rationale for the Structure and Model and
                Protocol for the Internet Printing Protocol", RFC 2568,
                April 1999.

   [RFC2569]    Herriot, R., Hastings, T., Jacobs, N. and J. Martin,
                "Mapping between LPD and IPP Protocols", RFC 2569, April
                1999.

   [RFC2579]    McCloghrie, K., Perkins, D. and J. Schoenwaelder,
                "Textual Conventions for SMIv2", STD 58, RFC 2579, April
                1999.

   [SSL]        Netscape, The SSL Protocol, Version 3, (Text version
                3.02), November 1996.

   [SWP]        P. Moore, B. Jahromi, S. Butler, "Simple Web Printing
                SWP/1.0", May 7, 1997,
                ftp://ftp.pwg.org/pub/pwg/ipp/new_PRO/swp9705.pdf

10. Authors' Addresses

   Scott A. Isaacson (Editor)
   Novell, Inc.
   122 E 1700 S
   Provo, UT   84606

   Phone: 801-861-7366
   Fax:   801-861-2517
   EMail: sisaacson@novell.com

   Tom Hastings
   Xerox Corporation
   737 Hawaii St.
   El Segundo, CA   90245

   Phone: 310-333-6413
   Fax:   310-333-5514
   EMail: hastings@cp10.es.xerox.com

   Robert Herriot
   Xerox Corporation
   3400 Hillview Ave., Bldg #1
   Palo Alto, CA 94304

   Phone: 650-813-7696
   Fax:  650-813-6860
   EMail: robert.herriot@pahv.xerox.com

   Roger deBry
   Utah Valley State College
   Orem, UT 84058

   Phone: (801) 222-8000
   EMail: debryro@uvsc.edu

   Patrick Powell
   Astart Technologies
   9475 Chesapeake Dr., Suite D
   San Diego, CA  95123

   Phone: (619) 874-6543
   Fax: (619) 279-8424
   EMail: papowell@astart.com

   IPP Mailing List:  ipp@pwg.org
   IPP Mailing List Subscription: ipp-request@pwg.org
   IPP Web Page:  http://www.pwg.org/ipp/

   Implementers of this specification are encouraged to join IPP Mailing
   List in order to participate in any discussions of clarification
   issues and review of registration proposals for additional attributes
   and values.

   Other Participants:

      Chuck Adams - Tektronix
      Jeff Barnett - IBM
      Ron Bergman - Dataproducts Corp.
      Sylvan Butler - HP
      Keith Carter - IBM Corporation
      Jeff Copeland - QMS
      Andy Davidson - Tektronix
      Mabry Dozier - QMS
      Lee Farrell - Canon Information Systems
      Steve Gebert - IBM
      Babek Jahromi - Microsoft
      David Kellerman - Northlake Software
      Rick Landau - Digital
      Greg LeClair - Epson
      Harry Lewis - IBM
      Pete Loya - HP
      Ray Lutz - Cognisys
      Mike MacKay - Novell, Inc.
      Daniel Manchala - Xerox
      Carl-Uno Manros - Xerox
      Jay Martin - Underscore
      Larry Masinter - Xerox
      Stan McConnell - Xerox
      Ira McDonald - High North Inc.
      Paul Moore - Microsoft
      Tetsuya Morita - Ricoh
      Yuichi Niwa - Ricoh
      Pat Nogay - IBM

      Ron Norton - Printronics
      Bob Pentecost - HP
      Rob Rhoads - Intel
      Xavier Riley - Xerox
      David Roach - Unisys
      Stuart Rowley - Kyocera
      Hiroyuki Sato - Canon
      Bob Setterbo - Adobe
      Devon Taylor - Novell, Inc.
      Mike Timperman - Lexmark
      Randy Turner - Sharp
      Atsushi Yuki - Kyocera
      Rick Yardumian - Xerox
      Lloyd Young - Lexmark
      Bill Wagner - DPI
      Jim Walker - DAZEL
      Chris Wellens - Interworking Labs
      Rob Whittle - Novell, Inc.
      Don Wright - Lexmark
      Peter Zehler - Xerox
      Steve Zilles - Adobe

11. Formats for IPP Registration Proposals

   In order to propose an IPP extension for registration, the proposer
   must submit an application to IANA by email to "iana@iana.org" or by
   filling out the appropriate form on the IANA web pages
   (http://www.iana.org).  This section specifies the required
   information and the formats for proposing registrations of extensions
   to IPP as provided in Section 6 for:

     1. type2 'keyword' attribute values
     2. type3 'keyword' attribute values
     3. type2 'enum' attribute values
     4. type3 'enum' attribute values
     5. attributes
     6. attribute syntaxes
     7. operations
     8. status codes

11.1 Type2 keyword attribute values registration

   Type of registration:  type2 keyword attribute value
   Name of attribute to which this keyword specification is to be added:
   Proposed keyword name of this keyword value:
   Specification of this keyword value (follow the style of IPP Model
   Section 4.1.2.3):
   Name of proposer:

   Address of proposer:
   Email address of proposer:

   Note:  For type2 keywords, the Designated Expert will be the point of
   contact for the approved registration specification, if any
   maintenance of the registration specification is needed.

11.2 Type3 keyword attribute values registration

   Type of registration:  type3 keyword attribute value
   Name of attribute to which this keyword specification is to be added:
   Proposed keyword name of this keyword value:
   Specification of this keyword value (follow the style of IPP Model
   Section 4.1.2.3):
   Name of proposer:
   Address of proposer:
   Email address of proposer:

   Note:  For type3 keywords, the proposer will be the point of contact
   for the approved registration specification, if any maintenance of
   the registration specification is needed.

11.3 Type2 enum attribute values registration

   Type of registration:  type2 enum attribute value
   Name of attribute to which this enum specification is to be added:
   Keyword symbolic name of this enum value:
   Numeric value (to be assigned by the IPP Designated Expert in
   consultation with IANA):
   Specification of this enum value (follow the style of IPP Model
   Section 4.1.4):
   Name of proposer:
   Address of proposer:
   Email address of proposer:

   Note:  For type2 enums, the Designated Expert will be the point of
   contact for the approved registration specification, if any
   maintenance of the registration specification is needed.

11.4 Type3 enum attribute values registration

   Type of registration:  type3 enum attribute value
   Name of attribute to which this enum specification is to be added:
   Keyword symbolic name of this enum value:
   Numeric value (to be assigned by the IPP Designated Expert in
   consultation with IANA):
   Specification of this enum value (follow the style of IPP Model
   Section 4.1.4):

   Name of proposer:
   Address of proposer:
   Email address of proposer:

   Note:  For type3 enums, the proposer will be the point of contact for
   the approved registration specification, if any maintenance of the
   registration specification is needed.

11.5 Attribute registration

   Type of registration:  attribute
   Proposed keyword name of this attribute:
   Types of attribute (Operation, Job Template, Job Description,
   Printer Description):
   Operations to be used with if the attribute is an operation
   attribute:
   Object (Job, Printer, etc. if bound to an object):
   Attribute syntax(es) (include 1setOf and range as in Section 4.2):
   If attribute syntax is 'keyword' or 'enum', is it type2 or type3:
   If this is a Printer attribute, MAY the value returned depend on
   "document-format" (See Section 6.2):
   If this is a Job Template attribute, how does its specification
   depend on the value of the "multiple-document-handling" attribute:
   Specification of this attribute (follow the style of IPP Model
   Section 4.2):
   Name of proposer:
   Address of proposer:
   Email address of proposer:

   Note:  For attributes, the IPP Designated Expert will be the point of
   contact for the approved registration specification, if any
   maintenance of the registration specification is needed.

11.6 Attribute Syntax registration

   Type of registration:  attribute syntax
   Proposed name of this attribute syntax:
   Type of attribute syntax (integer, octetString, character-string,
   see [RFC2565]):
   Numeric value (to be assigned by the IPP Designated Expert in
   consultation with IANA):
   Specification of this attribute (follow the style of IPP Model
   Section 4.1):
   Name of proposer:
   Address of proposer:
   Email address of proposer:

   Note:  For attribute syntaxes, the IPP Designated Expert will be the
   point of contact for the approved registration specification, if any
   maintenance of the registration specification is needed.

11.7 Operation registration

   Type of registration:  operation
   Proposed name of this operation:
   Numeric operation-id value (to be assigned by the IPP Designated
   Expert in consultation with IANA):
   Object Target (Job, Printer, etc. that operation is upon):
   Specification of this attribute (follow the style of IPP Model
   Section 3):
   Name of proposer:
   Address of proposer:
   Email address of proposer:

   Note:  For operations, the IPP Designated Expert will be the point of
   contact for the approved registration specification, if any
   maintenance of the registration specification is needed.

11.8 Attribute Group registration

   Type of registration:  attribute group
   Proposed name of this attribute group:
   Numeric tag according to [RFC2565] (to be assigned by the IPP
   Designated Expert in consultation with IANA):
   Operation requests and group number for each operation in which the
   attribute group occurs:
   Operation responses and group number for each operation in which the
   attribute group occurs:
   Specification of this attribute group (follow the style of IPP Model
   Section 3):
   Name of proposer:
   Address of proposer:
   Email address of proposer:

   Note:  For attribute groups, the IPP Designated Expert will be the
   point of contact for the approved registration specification, if any
   maintenance of the registration specification is needed.

11.9 Status code registration

   Type of registration:  status code
   Keyword symbolic name of this status code value:
   Numeric value (to be assigned by the IPP Designated Expert in
   consultation with IANA):
   Operations that this status code may be used with:

   Specification of this status code (follow the style of IPP Model
   Section 14 APPENDIX B:  Status Codes and Suggested Status Code
   Messages):
   Name of proposer:
   Address of proposer:
   Email address of proposer:

   Note:  For status codes, the Designated Expert will be the point of
   contact for the approved registration specification, if any
   maintenance of the registration specification is needed.

12. APPENDIX A: Terminology

   This specification uses the terminology defined in this section.

12.1 Conformance Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
   "RECOMMENDED", "MAY", and  "OPTIONAL" in this document are to be
   interpreted as described in RFC 2119 [RFC2119].

12.1.1 NEED NOT

   This term is not included in RFC 2119.  The verb "NEED NOT" indicates
   an action that the subject of the sentence does not have to implement
   in order to claim conformance to the standard.  The verb "NEED NOT"
   is used instead of "MAY NOT" since "MAY NOT" sounds like a
   prohibition.

12.2 Model Terminology

12.2.1 Keyword

   Keywords are used within this document as identifiers of semantic
   entities within the abstract model (see section 4.1.2.3).  Attribute
   names, some attribute values, attribute syntaxes, and attribute group
   names are represented as keywords.

12.2.2 Attributes

   An attribute is an item of information that is associated with an
   instance of an IPP object.  An attribute consists of an attribute
   name and one or more attribute values.  Each attribute has a specific
   attribute syntax.  All object attributes are defined in section 4 and
   all operation attributes are defined in section 3.

   Job Template Attributes are described in section 4.2. The client
   optionally supplies Job Template attributes in a create request
   (operation requests that create Job objects).  The Printer object has
   associated attributes which define supported and default values for
   the Printer.

12.2.2.1 Attribute Name

   Each attribute is uniquely identified in this document by its
   attribute name.  An attribute name is a keyword.  The keyword
   attribute name is given in the section header describing that

   attribute.  In running text in this document, attribute names are
   indicated inside double quotation marks (") where the quotation marks
   are not part of the keyword itself.

12.2.2.2 Attribute Group Name

   Related attributes are grouped into named groups.  The name of the
   group is a keyword.  The group name may be used in place of naming
   all the attributes in the group explicitly.  Attribute groups are
   defined in section 3.

12.2.2.3 Attribute Value

   Each attribute has one or more values.  Attribute values are
   represented in the syntax type specified for that attribute. In
   running text in this document, attribute values are indicated inside
   single quotation marks ('), whether their attribute syntax is
   keyword, integer, text, etc.  where the quotation marks are not part
   of the value itself.

12.2.2.4 Attribute Syntax

   Each attribute is defined using an explicit syntax type.  In this
   document, each syntax type is defined as a keyword with specific
   meaning.  The Encoding and Transport document [RFC2565] indicates the
   actual "on-the-wire" encoding rules for each syntax type.  Attribute
   syntax types are defined in section 4.1.

12.2.3 Supports

   By definition, a Printer object supports an attribute only if that
   Printer object responds with the corresponding attribute populated
   with some value(s) in a response to a query for that attribute.  A
   Printer object supports an attribute value if the value is one of the
   Printer object's "supported values" attributes.  The device behind a
   Printer object may exhibit a behavior that corresponds to some IPP
   attribute, but if the Printer object, when queried for that
   attribute, doesn't respond with the attribute, then as far as IPP is
   concerned, that implementation does not support that feature. If the
   Printer object's "xxx-supported" attribute is not populated with a
   particular value (even if that value is a legal value for that
   attribute), then that Printer object does not support that particular
   value.

   A conforming implementation MUST support all REQUIRED attributes.
   However, even for REQUIRED attributes, conformance to IPP does not
   mandate that all implementations support all possible values
   representing all possible job processing behaviors and features.  For

   example, if a given instance of a Printer supports only certain
   document formats, then that Printer responds with the "document-
   format-supported" attribute populated with a set of values, possibly
   only one, taken from the entire set of possible values defined for
   that attribute. This limited set of values represents the Printer's
   set of supported document formats.  Supporting an attribute and some
   set of values for that attribute enables IPP end users to be aware of
   and make use of those features associated with that attribute and
   those values.  If an implementation chooses to not support an
   attribute or some specific value, then IPP end users would have no
   ability to make use of that feature within the context of IPP itself.
   However, due to existing practice and legacy systems which are not
   IPP aware, there might be some other mechanism outside the scope of
   IPP to control or request the "unsupported" feature (such as embedded
   instructions within the document data itself).

   For example, consider the "finishings-supported" attribute.

     1) If a Printer object is not physically capable of stapling, the
        "finishings-supported" attribute MUST NOT be populated with the
        value of 'staple'.
     2) A Printer object is physically capable of stapling, however an
        implementation chooses not to support stapling in the IPP
        "finishings" attribute.  In this case, 'staple' MUST NOT be a
        value in the "finishings-supported" Printer object attribute.
        Without support for the value 'staple', an IPP end user would
        have no means within the protocol itself to request that a Job
        be stapled.  However, an existing document data formatter might
        be able to request that the document be stapled directly with an
        embedded instruction within the document data.  In this case,
        the IPP implementation does not "support" stapling, however the
        end user is still able to have some control over the stapling of
        the completed job.
     3) A Printer object is physically capable of stapling, and an
        implementation chooses to support stapling in the IPP
        "finishings" attribute. In this case, 'staple' MUST be a value
        in the "finishings-supported" Printer object attribute. Doing
        so, would enable end users to be aware of and make use of the
        stapling feature using IPP attributes.

   Even though support for Job Template attributes by a Printer object
   is OPTIONAL, it is RECOMMENDED that if the device behind a Printer
   object is capable of realizing any feature or function that
   corresponds to an IPP attribute and some associated value, then that
   implementation SHOULD support that IPP attribute and value.

   The set of values in any of the supported value attributes is set
   (populated) by some administrative process or automatic sensing
   mechanism that is outside the scope of IPP.  For administrative
   policy and control reasons, an administrator may choose to make only
   a subset of possible values visible to the end user.  In this case,
   the real output device behind the IPP Printer abstraction may be
   capable of a certain feature, however an administrator is specifying
   that access to that feature not be exposed to the end user through
   the IPP protocol.  Also, since a Printer object may represent a
   logical print device (not just a physical device) the actual process
   for supporting a value is undefined and left up to the
   implementation.  However, if a Printer object supports a value, some
   manual human action may be needed to realize the semantic action
   associated with the value, but no end user action is required.

   For example, if one of the values in the "finishings-supported"
   attribute is 'staple', the actual process might be an automatic
   staple action by a physical device controlled by some command sent to
   the device.  Or, the actual process of stapling might be a manual
   action by an operator at an operator attended Printer object.

   For another example of how supported attributes function, consider a
   system administrator who desires to control all print jobs so that no
   job sheets are printed in order to conserve paper.  To force no job
   sheets, the system administrator sets the only supported value for
   the "job-sheets-supported" attribute to 'none'.  In this case, if a
   client requests anything except 'none', the create request is
   rejected or the "job-sheets" value is ignored (depending on the value
   of "ipp-attribute-fidelity").  To force the use of job start/end
   sheets on all jobs, the administrator does not include the value '
   none' in the "job-sheets-supported" attribute.  In this case, if a
   client requests 'none', the create request is rejected or the "job-
   sheets" value is ignored (again depending on the value of "ipp-
   attribute-fidelity").

12.2.4 print-stream page

   A "print-stream page" is a page according to the definition of pages
   in the language used to express the document data.

12.2.5 impression

   An "impression" is the image (possibly many print-stream pages in
   different configurations) imposed onto a single media page.

13. APPENDIX B:  Status Codes and Suggested Status Code Messages

   This section defines status code enum keywords and values that are
   used to provide semantic information on the results of an operation
   request.  Each operation response MUST include a status code.  The
   response MAY also contain a status message that provides a short
   textual description of the status.  The status code is intended for
   use by automata, and the status message is intended for the human end
   user.  Since the status message is an OPTIONAL component of the
   operation response, an IPP application (i.e., a browser, GUI, print
   driver or gateway) is NOT REQUIRED to examine or display the status
   message, since it MAY not be returned to the application.

   The prefix of the status keyword defines the class of response as
   follows:

     "informational" - Request received, continuing process
     "successful" - The action was successfully received, understood,
        and accepted
     "redirection" - Further action must be taken in order to complete
        the request
     "client-error" - The request contains bad syntax or cannot be
        fulfilled
     "server-error" - The IPP object  failed to fulfill an apparently
        valid request

   As with type2 enums, IPP status codes are extensible.  IPP clients
   are NOT REQUIRED to understand the meaning of all registered status
   codes, though such understanding is obviously desirable.  However,
   IPP clients MUST understand the class of any status code, as
   indicated by the prefix, and treat any unrecognized response as being
   equivalent to the first status code of that class, with the exception
   that an unrecognized response MUST NOT be cached.  For example, if an
   unrecognized status code of "client-error-xxx-yyy" is received by the
   client, it can safely assume that there was something wrong with its
   request and treat the response as if it had received a "client-
   error-bad-request" status code.  In such cases, IPP applications
   SHOULD present the OPTIONAL message (if present) to the end user
   since the message is likely to contain human readable information
   which will help to explain the unusual status.  The name of the enum
   is the suggested status message for US English.

   The status code values range from 0x0000 to 0x7FFF.  The value ranges
   for each status code class are as follows:

     "successful" - 0x0000 to 0x00FF
     "informational" - 0x0100 to 0x01FF
     "redirection" - 0x0200 to 0x02FF

     "client-error" - 0x0400 to 0x04FF
     "server-error" - 0x0500 to 0x05FF

   The top half (128 values) of each range (0x0n40 to 0x0nFF, for n = 0
   to 5) is reserved for private use within each status code class.
   Values 0x0600 to 0x7FFF are reserved for future assignment and MUST
   NOT be used.

13.1 Status Codes

   Each status code is described below. Section 13.1.5.9 contains a
   table that indicates which status codes apply to which operations.
   The Implementer's Guide [ipp-iig] describe the suggested steps for
   processing IPP attributes for all operations, including returning
   status codes.

13.1.1 Informational

   This class of status code indicates a provisional response and is to
   be used for informational purposes only.

   There are no status codes defined in IPP/1.0 for this class of status
   code.

13.1.2 Successful Status Codes

   This class of status code indicates that the client's request was
   successfully received, understood, and accepted.

13.1.2.1 successful-ok (0x0000)

   The request has succeeded and no request attributes were substituted
   or ignored.  In the case of a response to a create request, the '
   successful-ok' status code indicates that the request was
   successfully received and validated, and that the Job object has been
   created; it does not indicate that the job has been processed.  The
   transition of the Job object into the 'completed' state is the only
   indicator that the job has been printed.

13.1.2.2 successful-ok-ignored-or-substituted-attributes (0x0001)

   The request has succeeded, but some supplied (1) attributes were
   ignored or (2) unsupported values were substituted with supported
   values or were ignored in order to perform the operation without
   rejecting it.  Unsupported attributes, attribute syntaxes, or values
   MUST be returned in the Unsupported Attributes group of the response
   for all operations.  There is an exception to this rule for the query
   operations:  Get-Printer-Attributes, Get-Jobs, and Get-Job-Attributes

   for the "requested-attributes" operation attribute only.  When the
   supplied values of the "requested-attributes" operation attribute are
   requesting attributes that are not supported, the IPP object MAY, but
   is NOT REQUIRED to, return the "requested-attributes" attribute in
   the Unsupported Attribute response group (with the unsupported values
   only).  See section 3.2.1.2.

13.1.2.3 successful-ok-conflicting-attributes (0x0002)

   The request has succeeded, but some supplied attribute values
   conflicted with the values of other supplied attributes.  These
   conflicting values were either (1) substituted with (supported)
   values or (2) the attributes were removed in order to process the job
   without rejecting it.  Attributes or values which conflict with other
   attributes and have been substituted or ignored MUST be returned in
   the Unsupported Attributes group of the response for all operations
   as supplied by the client.  See section 3.2.1.2.

13.1.3 Redirection Status Codes

   This class of status code indicates that further action needs to be
   taken to fulfill the request.

   There are no status codes defined in IPP/1.0 for this class of status
   code.

13.1.4 Client Error Status Codes

   This class of status code is intended for cases in which the client
   seems to have erred.  The IPP object SHOULD return a message
   containing an explanation of the error situation and whether it is a
   temporary or permanent condition.

13.1.4.1 client-error-bad-request (0x0400)

   The request could not be understood by the IPP object due to
   malformed syntax (such as the value of a fixed length attribute whose
   length does not match the prescribed length for that attribute - see
   the Implementer's Guide [ipp-iig] ).  The IPP application SHOULD NOT
   repeat the request without modifications.

13.1.4.2 client-error-forbidden (0x0401)

   The IPP object understood the request, but is refusing to fulfill it.
   Additional authentication information or authorization credentials
   will not help and the request SHOULD NOT be repeated.  This status

   code is commonly used when the IPP object does not wish to reveal
   exactly why the request has been refused or when no other response is
   applicable.

13.1.4.3 client-error-not-authenticated (0x0402)

   The request requires user authentication.  The IPP client may repeat
   the request with suitable authentication information. If the request
   already included authentication information, then this status code
   indicates that authorization has been refused for those credentials.
   If this response contains the same challenge as the prior response,
   and the user agent has already attempted authentication at least
   once, then the response message may contain relevant diagnostic
   information.  This status codes reveals more information than
   "client-error-forbidden".

13.1.4.4 client-error-not-authorized (0x0403)

   The requester is not authorized to perform the request.  Additional
   authentication information or authorization credentials will not help
   and the request SHOULD NOT be repeated.  This status code is used
   when the IPP object wishes to reveal that the authentication
   information is understandable, however, the requester is explicitly
   not authorized to perform the request.  This status codes reveals
   more information than "client-error-forbidden" and "client-error-
   not-authenticated".

13.1.4.5 client-error-not-possible (0x0404)

   This status code is used when the request is for something that can
   not happen.  For example, there might be a request to cancel a job
   that has already been canceled or aborted by the system.  The IPP
   client SHOULD NOT repeat the request.

13.1.4.6 client-error-timeout (0x0405)

   The client did not produce a request within the time that the IPP
   object was prepared to wait.  For example, a client issued a Create-
   Job operation and then, after a long period of time, issued a Send-
   Document operation and this error status code was returned in
   response to the Send-Document request  (see section 3.3.1).  The IPP
   object might have been forced to clean up resources that had been
   held for the waiting additional Documents.  The IPP object was forced
   to close the Job since the client took too long.  The client SHOULD
   NOT repeat the request without modifications.

13.1.4.7 client-error-not-found (0x0406)

   The IPP object has not found anything matching the request URI.  No
   indication is given of whether the condition is temporary or
   permanent.  For example, a client with an old reference to a Job (a
   URI) tries to cancel the Job, however in the mean time the Job might
   have been completed and all record of it at the Printer has been
   deleted.  This status code, 'client-error-not-found' is returned
   indicating that the referenced Job can not be found.  This error
   status code is also used when a client supplies a URI as a reference
   to the document data in either a Print-URI or Send-URI operation, but
   the document can not be found.

   In practice, an IPP application should avoid a not found situation by
   first querying and presenting a list of valid Printer URIs and Job
   URIs to the end-user.

13.1.4.8 client-error-gone (0x0407)

   The requested object is no longer available and no forwarding address
   is known.  This condition should be considered permanent.  Clients
   with link editing capabilities should delete references to the
   request URI after user approval.  If the IPP object does not know or
   has no facility to determine, whether or not the condition is
   permanent, the status code "client-error-not-found" should be used
   instead.

   This response is primarily intended to assist the task of maintenance
   by notifying the recipient that the resource is intentionally
   unavailable and that the IPP object administrator desires that remote
   links to that resource be removed. It is not necessary to mark all
   permanently unavailable resources as "gone" or to keep the mark for
   any length of time -- that is left to the discretion of the IPP
   object administrator.

13.1.4.9 client-error-request-entity-too-large (0x0408)

   The IPP object is refusing to process a request because the request
   entity is larger than the IPP object is willing or able to process.
   An IPP Printer returns this status code when it limits the size of
   print jobs and it receives a print job that exceeds that limit or
   when the attributes are so many that their encoding causes the
   request entity to exceed IPP object capacity.

13.1.4.10 client-error-request-value-too-long (0x0409)

   The IPP object is refusing to service the request because one or more
   of the client-supplied attributes has a variable length value that is
   longer than the maximum length specified for that attribute.  The IPP
   object might not have sufficient resources (memory, buffers, etc.) to
   process (even temporarily), interpret, and/or ignore a value larger
   than the maximum length.  Another use of this error code is when the
   IPP object supports the processing of a large value that is less than
   the maximum length, but during the processing of the request as a
   whole, the object may pass the value onto some other system component
   which is not able to accept the large value.  For more details, see
   the Implementer's Guide [ipp-iig] .

   Note:  For attribute values that are URIs, this rare condition is
   only likely to occur when a client has improperly submitted a request
   with long query information (e.g. an IPP application allows an end-
   user to enter an invalid URI), when the client has descended into a
   URI "black hole" of redirection (e.g., a redirected URI prefix that
   points to a suffix of itself), or when the IPP object is under attack
   by a client attempting to exploit security holes present in some IPP
   objects using fixed-length buffers for reading or manipulating the
   Request-URI.

13.1.4.11 client-error-document-format-not-supported (0x040A)

   The IPP object is refusing to service the request because the
   document data is in a format, as specified in the "document-format"
   operation attribute, that is not supported by the Printer object.
   This error is returned independent of the client-supplied "ipp-
   attribute-fidelity".  The Printer object MUST return this status
   code, even if there are other attributes that are not supported as
   well, since this error is a bigger problem than with Job Template
   attributes.

13.1.4.12 client-error-attributes-or-values-not-supported (0x040B)

   In a create request, if the Printer object does not support one or
   more attributes, attribute syntaxes, or attribute values supplied in
   the request and the client supplied the "ipp-attributes-fidelity"
   operation attribute with the 'true' value, the Printer object MUST
   return this status code.  For example, if the request indicates '
   iso-a4' media, but that media type is not supported by the Printer
   object.  Or, if the client supplies an optional attribute and the
   attribute itself is not even supported by the Printer.  If the "ipp-
   attribute-fidelity" attribute is 'false', the Printer MUST ignore or
   substitute values for unsupported attributes and values rather than
   reject the request and return this status code.

   For any operation where a client requests attributes (such as a Get-
   Jobs, Get-Printer-Attributes, or Get-Job-Attributes operation), if
   the IPP object does not support one or more of the requested
   attributes, the IPP object simply ignores the unsupported requested
   attributes and processes the request as if they had not been
   supplied, rather than returning this status code.  In this case, the
   IPP object MUST return the 'successful-ok-ignored-or-substituted-
   attributes' status code and MAY return the unsupported attributes as
   values of the "requested-attributes" in the Unsupported Attributes
   Group (see section 13.1.2.2).

13.1.4.13 client-error-uri-scheme-not-supported (0x040C)

   The type of the client supplied URI in a Print-URI or a Send-URI
   operation is not supported.

13.1.4.14 client-error-charset-not-supported (0x040D)

   For any operation, if the IPP Printer does not support the charset
   supplied by the client in the "attributes-charset" operation
   attribute, the Printer MUST reject the operation and return this
   status and any 'text' or 'name' attributes using the 'utf-8' charset
   (see Section 3.1.4.1).

13.1.4.15 client-error-conflicting-attributes (0x040E)

   The request is rejected because some attribute values conflicted with
   the values of other attributes which this specification does not
   permit to be substituted or ignored.

13.1.5 Server Error Status Codes

   This class of status codes indicates cases in which the IPP object is
   aware that it has erred or is incapable of performing the request.
   The IPP object SHOULD include a message containing an explanation of
   the error situation, and whether it is a temporary or permanent
   condition.

13.1.5.1 server-error-internal-error (0x0500)

   The IPP object encountered an unexpected condition that prevented it
   from fulfilling the request.  This error status code differs from
   "server-error-temporary-error" in that it implies a more permanent
   type of internal error.  It also differs from "server-error-device-
   error" in that it implies an unexpected condition (unlike a paper-jam
   or out-of-toner problem which is undesirable but expected).  This
   error status code indicates that probably some knowledgeable human
   intervention is required.

13.1.5.2 server-error-operation-not-supported (0x0501)

   The IPP object does not support the functionality required to fulfill
   the request. This is the appropriate response when the IPP object
   does not recognize an operation or is not capable of supporting it.

13.1.5.3 server-error-service-unavailable (0x0502)

   The IPP object is currently unable to handle the request due to a
   temporary overloading or maintenance of the IPP object.  The
   implication is that this is a temporary condition which will be
   alleviated after some delay. If known, the length of the delay may be
   indicated in the message.  If no delay is given, the IPP application
   should handle the response as it would for a "server-error-
   temporary-error" response.  If the condition is more permanent, the
   error status codes "client-error-gone" or "client-error-not-found"
   could be used.

13.1.5.4 server-error-version-not-supported (0x0503)

   The IPP object does not support, or refuses to support, the IPP
   protocol version that was used in the request message.  The IPP
   object is indicating that it is unable or unwilling to complete the
   request using the same version as supplied in the request other than
   with this error message. The response should contain a Message
   describing why that version is not supported and what other versions
   are supported by that IPP object.

   A conforming IPP/1.0 client MUST specify the valid version ('1.0') on
   each request.  A conforming IPP/1.0 object MUST NOT return this
   status code to a conforming IPP/1.0 client.  An IPP object MUST
   return this status code to a non-conforming IPP client.  The response
   MUST identify in the "version-number" operation attribute the closest
   version number that the IPP object does support.

13.1.5.5 server-error-device-error (0x0504)

   A printer error, such as a paper jam, occurs while the IPP object
   processes a Print or Send operation.  The response contains the true
   Job Status (the values of the "job-state" and "job-state-reasons"
   attributes).  Additional information can be returned in the optional
   "job-state-message" attribute value or in the OPTIONAL status message
   that describes the error in more detail.  This error status code is
   only returned in situations where the Printer is unable to accept the
   create request because of such a device error.  For example, if the
   Printer is unable to spool, and can only accept one job at a time,
   the reason it might reject a create request is that the printer
   currently has a paper jam.  In many cases however, where the Printer

   object can accept the request even though the Printer has some error
   condition, the 'successful-ok' status code will be returned.  In such
   a case, the client would look at the returned Job Object Attributes
   or later query the Printer to determine its state and state reasons.

13.1.5.6 server-error-temporary-error (0x0505)

   A temporary error such as a buffer full write error, a memory
   overflow (i.e. the document data exceeds the memory of the Printer),
   or a disk full condition, occurs while the IPP Printer processes an
   operation.  The client MAY try the unmodified request again at some
   later point in time with an expectation that the temporary internal
   error condition may have been cleared.  Alternatively, as an
   implementation option, a Printer object MAY delay the response until
   the temporary condition is cleared so that no error is returned.

13.1.5.7 server-error-not-accepting-jobs (0x0506)

   A temporary error indicating that the Printer is not currently
   accepting jobs, because the administrator has set the value of the
   Printer's "printer-is-not-accepting-jobs" attribute to 'false' (by
   means outside of IPP/1.0).

13.1.5.8 server-error-busy (0x0507)

   A temporary error indicating that the Printer is too busy processing
   jobs and/or other requests. The client SHOULD try the unmodified
   request again at some later point in time with an expectation that
   the temporary busy condition will have been cleared.

13.1.5.9 server-error-job-canceled (0x0508)

   An error indicating that the job has been canceled by an operator or
   the system while the client was transmitting the data to the IPP
   Printer.  If a job-id and job-uri had been created, then they are
   returned in the Print-Job, Send-Document, or Send-URI response as
   usual; otherwise, no job-id and job-uri are returned in the response.

13.2 Status Codes for IPP Operations

   PJ = Print-Job, PU = Print-URI, CJ = Create-Job, SD = Send-Document
   SU = Send-URI, V = Validate-Job, GA = Get-Job-Attributes and
   Get-Printer-Attributes, GJ = Get-Jobs, C = Cancel-Job

                                                  IPP Operations
   IPP Status Keyword                       PJ PU CJ SD SU V GA GJ C
   ------------------                       -- -- -- -- -- - -- -- -
   successful-ok                            x  x  x  x  x  x x  x  x
   successful-ok-ignored-or-substituted-    x  x  x  x  x  x x  x  x
        attributes
   successful-ok-conflicting-attributes     x  x  x  x  x  x x  x  x
   client-error-bad-request                 x  x  x  x  x  x x  x  x
   client-error-forbidden                   x  x  x  x  x  x x  x  x
   client-error-not-authenticated           x  x  x  x  x  x x  x  x
   client-error-not-authorized              x  x  x  x  x  x x  x  x
   client-error-not-possible                x  x  x  x  x  x x  x  x
   client-error-timeout                           x  x
   client-error-not-found                   x  x  x  x  x  x x  x  x
   client-error-gone                        x  x  x  x  x  x x  x  x
   client-error-request-entity-too-large    x  x  x  x  x  x x  x  x
   client-error-request-value-too-long      x  x  x  x  x  x x  x  x
   client-error-document-format-not-        x  x     x  x  x x
        supported
   client-error-attributes-or-values-not-   x  x  x  x  x  x x  x  x
        supported
   client-error-uri-scheme-not-supported       x        x
   client-error-charset-not-supported       x  x  x  x  x  x x  x  x
   client-error-conflicting-attributes      x  x  x  x  x  x x  x  x
   server-error-internal-error              x  x  x  x  x  x x  x  x
   server-error-operation-not-supported        x  x  x  x
   server-error-service-unavailable         x  x  x  x  x  x x  x  x
   server-error-version-not-supported       x  x  x  x  x  x x  x  x
   server-error-device-error                x  x  x  x  x
   server-error-temporary-error             x  x  x  x  x
   server-error-not-accepting-jobs          x  x  x        x
   server-error-busy                        x  x  x  x  x  x x  x  x
   server-error-job-canceled                x        x

14. APPENDIX C:  "media" keyword values

   Standard keyword values are taken from several sources.

   Standard values are defined (taken from DPA[ISO10175] and the Printer
   MIB[RFC1759]):

     'default': The default medium for the output device
     'iso-a4-white': Specifies the ISO A4 white medium
     'iso-a4-colored': Specifies the ISO A4 colored medium
     'iso-a4-transparent' Specifies the ISO A4 transparent medium
     'iso-a3-white': Specifies the ISO A3 white medium
     'iso-a3-colored': Specifies the ISO A3 colored medium
     'iso-a5-white': Specifies the ISO A5 white medium
     'iso-a5-colored': Specifies the ISO A5 colored medium
     'iso-b4-white': Specifies the ISO B4 white medium
     'iso-b4-colored': Specifies the ISO B4 colored medium
     'iso-b5-white': Specifies the ISO B5 white medium
     'iso-b5-colored': Specifies the ISO B5 colored medium
     'jis-b4-white': Specifies the JIS B4 white medium
     'jis-b4-colored': Specifies the JIS B4 colored medium
     'jis-b5-white': Specifies the JIS B5 white medium
     'jis-b5-colored': Specifies the JIS B5 colored medium

   The following standard values are defined for North American media:

     'na-letter-white': Specifies the North American letter white medium
     'na-letter-colored': Specifies the North American letter colored
        medium
     'na-letter-transparent': Specifies the North American letter
        transparent medium
     'na-legal-white': Specifies the North American legal white medium
     'na-legal-colored': Specifies the North American legal colored
        medium

   The following standard values are defined for envelopes:

     'iso-b4-envelope': Specifies the ISO B4 envelope medium
     'iso-b5-envelope': Specifies the ISO B5 envelope medium
     'iso-c3-envelope': Specifies the ISO C3 envelope medium
     'iso-c4-envelope': Specifies the ISO C4 envelope medium
     'iso-c5-envelope': Specifies the ISO C5 envelope medium
     'iso-c6-envelope': Specifies the ISO C6 envelope medium
     'iso-designated-long-envelope': Specifies the ISO Designated Long
        envelope medium
     'na-10x13-envelope': Specifies the North American 10x13 envelope
        medium

     'na-9x12-envelope': Specifies the North American 9x12 envelope
        medium
     'monarch-envelope': Specifies the Monarch envelope
     'na-number-10-envelope': Specifies the North American number 10
        business envelope medium
     'na-7x9-envelope': Specifies the North American 7x9 inch envelope
     'na-9x11-envelope': Specifies the North American 9x11 inch envelope
     'na-10x14-envelope': Specifies the North American 10x14 inch
        envelope
     'na-number-9-envelope': Specifies the North American number 9
        business envelope
     'na-6x9-envelope': Specifies the North American 6x9 inch envelope
     'na-10x15-envelope': Specifies the North American 10x15 inch
        envelope

   The following standard values are defined for the less commonly used
   media (white-only):

     'executive-white': Specifies the white executive medium
     'folio-white': Specifies the folio white medium
     'invoice-white': Specifies the white invoice medium
     'ledger-white': Specifies the white ledger medium
     'quarto-white': Specified the white quarto medium
     'iso-a0-white': Specifies the ISO A0 white medium
     'iso-a1-white': Specifies the ISO A1 white medium
     'iso-a2-white': Specifies the ISO A2 white medium
     'iso-a6-white': Specifies the ISO A6 white medium
     'iso-a7-white': Specifies the ISO A7 white medium
     'iso-a8-white': Specifies the ISO A8 white medium
     'iso-a9-white': Specifies the ISO A9 white medium
     'iso-10-white': Specifies the ISO A10 white medium
     'iso-b0-white': Specifies the ISO B0 white medium
     'iso-b1-white': Specifies the ISO B1 white medium
     'iso-b2-white': Specifies the ISO B2 white medium
     'iso-b3-white': Specifies the ISO B3 white medium
     'iso-b6-white': Specifies the ISO B6 white medium
     'iso-b7-white': Specifies the ISO B7 white medium
     'iso-b8-white': Specifies the ISO B8 white medium
     'iso-b9-white': Specifies the ISO B9 white medium
     'iso-b10-white': Specifies the ISO B10 white medium
     'jis-b0-white': Specifies the JIS B0 white medium
     'jis-b1-white': Specifies the JIS B1 white medium
     'jis-b2-white': Specifies the JIS B2 white medium
     'jis-b3-white': Specifies the JIS B3 white medium
     'jis-b6-white': Specifies the JIS B6 white medium
     'jis-b7-white': Specifies the JIS B7 white medium

     'jis-b8-white': Specifies the JIS B8 white medium
     'jis-b9-white': Specifies the JIS B9 white medium
     'jis-b10-white': Specifies the JIS B10 white medium

   The following standard values are defined for engineering media:

     'a': Specifies the engineering A size medium
     'b': Specifies the engineering B size medium
     'c': Specifies the engineering C size medium
     'd': Specifies the engineering D size medium
     'e': Specifies the engineering E size medium

   The following standard values are defined for input-trays (from ISO
   DPA and the Printer MIB):

     'top': The top input tray in the printer.
     'middle': The middle input tray in the printer.
     'bottom': The bottom input tray in the printer.
     'envelope': The envelope input tray in the printer.
     'manual': The manual feed input tray in the printer.
     'large-capacity': The large capacity input tray in the printer.
     'main': The main input tray
     'side': The side input tray

   The following standard values are defined for media sizes (from ISO
   DPA):

     'iso-a0': Specifies the ISO A0 size: 841 mm by 1189 mm as defined
        in ISO 216
     'iso-a1': Specifies the ISO A1 size: 594 mm by 841 mm as defined in
        ISO 216
     'iso-a2': Specifies the ISO A2 size: 420 mm by 594 mm as defined in
        ISO 216
     'iso-a3': Specifies the ISO A3 size: 297 mm by 420 mm as defined in
        ISO 216
     'iso-a4': Specifies the ISO A4 size: 210 mm by 297 mm as defined in
        ISO 216
     'iso-a5': Specifies the ISO A5 size: 148 mm by 210 mm as defined in
        ISO 216
     'iso-a6': Specifies the ISO A6 size: 105 mm by 148 mm as defined in
        ISO 216
     'iso-a7': Specifies the ISO A7 size: 74 mm by 105 mm as defined in
        ISO 216
     'iso-a8': Specifies the ISO A8 size: 52 mm by 74 mm as defined in
        ISO 216

     'iso-a9': Specifies the ISO A9 size: 37 mm by 52 mm as defined in
        ISO 216
     'iso-a10': Specifies the ISO A10 size: 26 mm by 37 mm as defined in
        ISO 216
     'iso-b0': Specifies the ISO B0 size: 1000 mm by 1414 mm as defined
        in ISO 216
     'iso-b1': Specifies the ISO B1 size: 707 mm by 1000 mm as defined
        in ISO 216
     'iso-b2': Specifies the ISO B2 size: 500 mm by 707 mm as defined in
        ISO 216
     'iso-b3': Specifies the ISO B3 size: 353 mm by 500 mm as defined in
        ISO 216
     'iso-b4': Specifies the ISO B4 size: 250 mm by 353 mm as defined in
        ISO 216
     'iso-b5': Specifies the ISO B5 size: 176 mm by 250 mm as defined in
        ISO 216
     'iso-b6': Specifies the ISO B6 size: 125 mm by 176 mm as defined in
        ISO 216
     'iso-b7': Specifies the ISO B7 size: 88 mm by 125 mm as defined in
        ISO 216
     'iso-b8': Specifies the ISO B8 size: 62 mm by 88 mm as defined in
        ISO 216
     'iso-b9': Specifies the ISO B9 size: 44 mm by 62 mm as defined in
        ISO 216
     'iso-b10': Specifies the ISO B10 size: 31 mm by 44 mm as defined in
        ISO 216
     'na-letter': Specifies the North American letter size: 8.5 inches by
        11 inches
     'na-legal': Specifies the North American legal size: 8.5 inches by
        14 inches
     'executive': Specifies the executive size (7.25 X 10.5 in)
     'folio': Specifies the folio size (8.5 X 13 in)
     'invoice': Specifies the invoice size (5.5 X 8.5 in)
     'ledger': Specifies the ledger size (11 X 17 in)
     'quarto': Specifies the quarto size (8.5 X 10.83 in)
     'iso-c3': Specifies the ISO C3 size: 324 mm by 458 mm as defined in
        ISO 269
     'iso-c4': Specifies the ISO C4 size: 229 mm by 324 mm as defined in
        ISO 269
     'iso-c5': Specifies the ISO C5 size: 162 mm by 229 mm as defined in
        ISO 269
     'iso-c6': Specifies the ISO C6 size: 114 mm by 162 mm as defined in
        ISO 269
     'iso-designated-long': Specifies the ISO Designated Long size: 110
        mm by 220 mm as defined in ISO 269
     'na-10x13-envelope': Specifies the North American 10x13 size: 10
        inches by 13 inches

     'na-9x12-envelope': Specifies the North American 9x12 size: 9
        inches by 12 inches
     'na-number-10-envelope': Specifies the North American number 10
        business envelope size: 4.125 inches by 9.5 inches
     'na-7x9-envelope': Specifies the North American 7x9 inch envelope
        size
     'na-9x11-envelope': Specifies the North American 9x11 inch envelope
        size
     'na-10x14-envelope': Specifies the North American 10x14 inch
        envelope size
     'na-number-9-envelope': Specifies the North American number 9
        business envelope size
     'na-6x9-envelope': Specifies the North American 6x9 envelope size
     'na-10x15-envelope': Specifies the North American 10x15 envelope
        size
     'monarch-envelope': Specifies the Monarch envelope size (3.87 x 7.5
        in)
     'jis-b0': Specifies the JIS B0 size: 1030mm x 1456mm
     'jis-b1': Specifies the JIS B1 size: 728mm x 1030mm
     'jis-b2': Specifies the JIS B2 size: 515mm x 728mm
     'jis-b3': Specifies the JIS B3 size: 364mm x 515mm
     'jis-b4': Specifies the JIS B4 size: 257mm x 364mm
     'jis-b5': Specifies the JIS B5 size: 182mm x 257mm
     'jis-b6': Specifies the JIS B6 size: 128mm x 182mm
     'jis-b7': Specifies the JIS B7 size: 91mm x 128mm
     'jis-b8': Specifies the JIS B8 size: 64mm x 91mm
     'jis-b9': Specifies the JIS B9 size: 45mm x 64mm
     'jis-b10': Specifies the JIS B10 size: 32mm x 45mm

15. APPENDIX D: Processing IPP Attributes

   When submitting a print job to a Printer object, the IPP model allows
   a client to supply operation and Job Template attributes along with
   the document data.  These Job Template attributes in the create
   request affect the rendering, production and finishing of the
   documents in the job.  Similar types of instructions may also be
   contained in the document to be printed, that is, embedded within the
   print data itself.  In addition, the Printer has a set of attributes
   that describe what rendering and finishing options which are
   supported by that Printer.  This model, which allows for flexibility
   and power, also introduces the potential that at job submission time,
   these client-supplied attributes may conflict with either:

     - what the implementation is capable of realizing (i.e., what the
       Printer supports), as well as
     - the instructions embedded within the print data itself.

   The following sections describe how these two types of conflicts are
   handled in the IPP model.

15.1 Fidelity

   If there is a conflict between what the client requests and what a
   Printer object supports, the client may request one of two possible
   conflict handling mechanisms:

     1) either reject the job since the job can not be processed exactly
        as specified, or
     2) allow the Printer to make any changes necessary to proceed with
        processing the Job the best it can.

   In the first case the client is indicating to the Printer object:
   "Print the job exactly as specified with no exceptions, and if that
   can't be done, don't even bother printing the job at all." In the
   second case, the client is indicating to the Printer object: "It is
   more important to make sure the job is printed rather than be
   processed exactly as specified; just make sure the job is printed
   even if client supplied attributes need to be changed or ignored."

   The IPP model accounts for this situation by introducing an "ipp-
   attribute-fidelity" attribute.

   In a create request, "ipp-attribute-fidelity" is a boolean operation
   attribute that is OPTIONALLY supplied by the client.  The value '
   true' indicates that total fidelity to client supplied Job Template
   attributes and values is required.  The client is requesting that the
   Job be printed exactly as specified, and if that is not possible then

   the job MUST be rejected rather than processed incorrectly.  The
   value 'false' indicates that a reasonable attempt to print the Job is
   acceptable.  If a Printer does not support some of the client
   supplied Job Template attributes or values, the Printer MUST ignore
   them or substitute any supported value for unsupported values,
   respectively.  The Printer may choose to substitute the default value
   associated with that attribute, or use some other supported value
   that is similar to the unsupported requested value.  For example, if
   a client supplies a "media" value of 'na-letter', the Printer may
   choose to substitute 'iso-a4' rather than a default value of '
   envelope'. If the client does not supply the "ipp-attribute-fidelity"
   attribute, the Printer assumes a value of 'false'.

   Each Printer implementation MUST support both types of "fidelity"
   printing (that is whether the client supplies a value of 'true' or '
   false'):

     - If the client supplies 'false' or does not supply the attribute,
       the Printer object MUST always accept the request by ignoring
       unsupported Job Template attributes and by substituting
       unsupported values of supported Job Template attributes with
       supported values.
     - If the client supplies 'true', the Printer object MUST reject the
       request if the client supplies unsupported Job Template
       attributes.

   Since a client can always query a Printer to find out exactly what is
   and is not supported, "ipp-attribute-fidelity" set to 'false' is
   useful when:

     1) The End-User uses a command line interface to request attributes
        that might not be supported.
     2) In a GUI context, if the End User expects the job might be moved
        to another printer and prefers a sub-optimal result to nothing
        at all.
     3) The End User just wants something reasonable in lieu of nothing
        at all.

15.2 Page Description Language (PDL) Override

   If there is a conflict between the value of an IPP Job Template
   attribute and a corresponding instruction in the document data, the
   value of the IPP attribute SHOULD take precedence over the document
   instruction.  Consider the case where a previously formatted file of
   document data is sent to an IPP Printer.  In this case, if the client
   supplies any attributes at job submission time, the client desires
   that those attributes override the embedded instructions.  Consider
   the case were a previously formatted document has embedded in it

   commands to load 'iso-a4' media.  However, the document is passed to
   an end user that only has access to a printer with 'na-letter' media
   loaded.  That end user most likely wants to submit that document to
   an IPP Printer with the "media" Job Template attribute set to 'na-
   letter'.  The job submission attribute should take precedence over
   the embedded PDL instruction.  However, until companies that supply
   document data interpreters allow a way for external IPP attributes to
   take precedence over embedded job production instructions, a Printer
   might not be able to support the semantics that IPP attributes
   override the embedded instructions.

   The IPP model accounts for this situation by introducing a "pdl-
   override-supported" attribute that describes the Printer objects
   capabilities to override instructions embedded in the PDL data
   stream.  The value of the "pdl-override-supported" attribute is
   configured by means outside IPP/1.0.

   This REQUIRED Printer attribute takes on the following values:

     - 'attempted': This value indicates that the Printer object
       attempts to make the IPP attribute values take precedence over
       embedded instructions in the document data, however there is no
       guarantee.
     - 'not-attempted': This value indicates that the Printer object
       makes no attempt to make the IPP attribute values take precedence
       over embedded instructions in the document data.

   At job processing time, an implementation that supports the value of
   'attempted' might do one of several different actions:

     1) Generate an output device specific command sequence to realize
        the feature represented by the IPP attribute value.
     2) Parse the document data itself and replace the conflicting
        embedded instruction with a new embedded instruction that
        matches the intent of the IPP attribute value.
     3) Indicate to the Printer that external supplied attributes take
        precedence over embedded instructions and then pass the external
        IPP attribute values to the document data interpreter.
     4) Anything else that allows for the semantics that IPP attributes
        override embedded document data instructions.

   Since 'attempted' does not offer any type of guarantee, even though a
   given Printer object might not do a very "good" job of attempting to
   ensure that IPP attributes take a higher precedence over instructions
   embedded in the document data, it would still be a conforming
   implementation.

   At job processing time, an implementation that supports the value of
   'not-attempted' might do one of the following actions:

     1) Simply pre-pend the document data with the PDL instruction that
        corresponds to the client-supplied PDL attribute, such that if
        the document data also has the same PDL instruction, it will
        override what the Printer object pre-pended.  In other words,
        this implementation is using the same implementation semantics
        for the client-supplied IPP attributes as for the Printer object
        defaults.
     2) Parse the document data and replace the conflicting embedded
        instruction with a new embedded instruction that approximates,
        but does not match, the semantic intent of the IPP attribute
        value.

   Note:  The "ipp-attribute-fidelity" attribute applies to the
   Printer's ability to either accept or reject other unsupported Job
   Template attributes.  In other words, if "ipp-attribute-fidelity" is
   set to 'true', a Job is accepted if and only if the client supplied
   Job Template attributes and values are supported by the Printer.
   Whether these attributes actually affect the processing of the Job
   when the document data contains embedded instructions depends on the
   ability of the Printer to override the instructions embedded in the
   document data with the semantics of the IPP attributes.  If the
   document data attributes can be overridden ("pdl-override-supported"
   set to 'attempted'), the Printer makes an attempt to use the IPP
   attributes when processing the Job. If the document data attributes
   can not be overridden ("pdl-override-supported" set to 'not-
   attempted'), the Printer makes no attempt to override the embedded
   document data instructions with the IPP attributes when processing
   the Job, and hence, the IPP attributes may fail to affect the Job
   processing and output when the corresponding instruction is embedded
   in the document data.

15.3 Using Job Template Attributes During Document Processing.

   The Printer object uses some of the Job object's Job Template
   attributes during the processing of the document data associated with
   that job.  These include, but are not limited to, "orientation",
   "number-up", "sides", "media", and "copies".  The processing of each
   document in a Job Object MUST follow the steps below. These steps are
   intended only to identify when and how attributes are to be used in
   processing document data and any alternative steps that accomplishes
   the same effect can be used to implement this specification.

     1. Using the client supplied "document-format" attribute or some
        form of document format detection algorithm (if the value of
        "document- format" is not specific enough), determine whether or

        not the document data has already been formatted for printing.
        If the document data has been formatted, then go to step 2.
        Otherwise, the document data MUST be formatted. The formatting
        detection algorithm is implementation defined and is not
        specified by this specification. The formatting of the document
        data uses the "orientation-requested" attribute to determine how
        the formatted print data should be placed on a print-stream
        page, see section 4.2.10 for the details.

     2. The document data is in the form of a print-stream in a known
        media type. The "page-ranges" attribute is used to select, as
        specified in section 4.2.7, a sub-sequence of the pages in the
        print-stream that are to be processed and images.

     3. The input to this step is a sequence of print-stream pages. This
        step is controlled by the "number-up" attribute. If the value of
        "number-up" is N, then during the processing of the print-stream
        pages, each N print-stream pages are positioned, as specified in
        section 4.2.9, to create a single impression. If a given
        document does not have N more print-stream pages, then the
        completion of the impression is controlled by the "multiple-
        document-handling" attribute as described in section 4.2.4; when
        the value of this attribute is 'single-document' or 'single-
        document-new-sheet', the print-stream pages of document data
        from subsequent documents is used to complete the impression.

        The size(scaling), position(translation) and rotation of the
        print-stream pages on the impression is implementation defined.
        Note that during this process the print-stream pages may be
        rendered to a form suitable for placing on the impression; this
        rendering is controlled by the values of the "printer-
        resolution" and "print- quality" attributes as described in
        sections 4.2.12 and 4.2.13. In the case N=1, the impression is
        nearly the same as the print-stream page; the differences would
        only be in the size, position and rotation of the print-stream
        page and/or any decoration, such as a frame to the page, that is
        added by the implementation.

     4. The collection of impressions is placed, in sequence, onto sides
        of the media sheets. This placement is controlled by the "sides"
        attribute and the orientation of the print-stream page, as
        described in section 4.2.8. The orientation of the print-stream
        pages affects the orientation of the impression; for example, if
        "number-up" equals 2, then, typically, two portrait print-stream
        pages become one landscape impression. Note that the placement
        of impressions onto media sheets is also controlled by the
        "multiple-document-handling" attribute as described in section
        4.2.4.

     5. The "copies" and "multiple-document-handling" attributes are
        used to determine how many copies of each media instance are
        created and in what order. See sections 4.2.5 and 4.2.4 for the
        details.

     6. When the correct number of copies are created, the media
        instances are finished according to the values of the
        "finishings" attribute as described in 4.2.6. Note that
        sometimes finishing operations may require manual intervention
        to perform the finishing operations on the copies, especially
        uncollated copies. This specification allows any or all of the
        processing steps to be performed automatically or manually at
        the discretion of the Printer object.

16. APPENDIX E: Generic Directory Schema

   This section defines a generic schema for an entry in a directory
   service.  A directory service is a means by which service users can
   locate service providers.  In IPP environments, this means that IPP
   Printers can be registered (either automatically or with the help of
   an administrator) as entries of type printer in the directory using
   an implementation specific mechanism such as entry attributes, entry
   type fields, specific branches, etc.  IPP clients can search or
   browse for entries of type printer.  Clients use the directory
   service to find entries based on naming, organizational contexts, or
   filtered searches on attribute values of entries.  For example, a
   client can find all printers in the "Local Department" context.
   Authentication and authorization are also often part of a directory
   service so that an administrator can place limits on end users so
   that they are only allowed to find entries to which they have certain
   access rights.  IPP itself does not require any specific directory
   service protocol or provider.

   Note: Some directory implementations allow for the notion of
   "aliasing".  That is, one directory entry object can appear as
   multiple directory entry object with different names for each object.
   In each case, each alias refers to the same directory entry object
   which refers to a single IPP Printer object.

   The generic schema is a subset of IPP Printer Job Template and
   Printer Description attributes (sections 4.2 and 4.4).  These
   attributes are identified as either RECOMMENDED or OPTIONAL for the
   directory entry itself.  This conformance labeling is NOT the same
   conformance labeling applied to the attributes of IPP Printers
   objects.  The conformance labeling in this Appendix is intended to
   apply to directory templates and to IPP Printer implementations that
   subscribe by adding one or more entries to a directory.  RECOMMENDED
   attributes SHOULD be associated with each directory entry.  OPTIONAL
   attributes MAY be associated with the directory entry (if known or
   supported).  In addition, all directory entry attributes SHOULD
   reflect the current attribute values for the corresponding Printer
   object.

   The names of attributes in directory schema and entries SHOULD be the
   same as the IPP Printer attribute names as shown.

   In order to bridge between the directory service and the IPP Printer
   object, one of the RECOMMENDED directory entry attributes is the
   Printer object's "printer-uri-supported" attribute.  The IPP client
   queries the "printer-uri-supported" attribute in the directory entry

   and then addresses the IPP Printer object using one of its URIs.  The
   "uri-security-supported" attribute identifies the protocol (if any)
   used to secure a channel.

   The following attributes define the generic schema for directory
   entries of type PRINTER:

     printer-uri-supported           RECOMMENDED    Section 4.4.1
     uri-security-supported          RECOMMENDED    Section 4.4.2
     printer-name                    RECOMMENDED    Section 4.4.3
     printer-location                RECOMMENDED    Section 4.4.4
     printer-info                    OPTIONAL       Section 4.4.5
     printer-more-info               OPTIONAL       Section 4.4.6
     printer-make-and-model          RECOMMENDED    Section 4.4.8
     charset-supported               OPTIONAL       Section 4.4.15
     generated-natural-language-
        supported                    OPTIONAL       Section 4.4.17
     document-format-supported       RECOMMENDED    Section 4.4.19
     color-supported                 RECOMMENDED    Section 4.4.23
     finishings-supported            OPTIONAL       Section 4.2.6
     number-up-supported             OPTIONAL       Section 4.2.7
     sides-supported                 RECOMMENDED    Section 4.2.8
     media-supported                 RECOMMENDED    Section 4.2.11
     printer-resolution-supported    OPTIONAL       Section 4.2.12
     print-quality-supported         OPTIONAL       Section 4.2.13

17. APPENDIX F:  Change History for the IPP Model and Semantics document

   The following substantive changes and major clarifications have been
   made to this document from the June 30, 1998 version based on the
   interoperability testing that took place September 23-25 1998 and
   subsequent mailing list and meeting discussions.  They are listed in
   the order of occurrence in the document.  These changes are the ones
   that might affect implementations.  Clarifications that are unlikely
   to affect implementations are not listed.  The issue numbers refer to
   the IPP Issues List which is available in the following directory:

        ftp://ftp.pwg.org/pub/pwg/ipp/approved-clarifications/

   Section   Description

   global    Replaced TLS references with SSL3 references as agreed with
             our Area Director on 11/12/1998.

   global    Removed the indications that some of these IPP documents
             are informational, since the intent is now to publish all
             IPP/1.0 documents as informational as agreed with our Area
             Director on 11/12/1998.

   3.1.2,    Clarify that the IPP object SHOULD NOT validate the
   16.3.3    range of the request-id being 1 to 2**31-1, but accepts
   [now ipp- and returns any value.  Clients MUST still keep in the
   iig]      range 1 to 2**31 though.  If the request is terminated
             before the complete "request-id" is received, the IPP
             object rejects the request and returns a response with a
             "request-id" of 0  (Issue 1.36).

   3.1.4.1,  Clarified that when a client submits a request in a
   13.1.4.14 charset that is not supported, the IPP object SHOULD
             return any 'text' or 'name' attributes in the 'utf-8'
             charset, if it returns any, since clients and IPP
             objects MUST support 'utf-8'.  (Issue 1.19)

   3.1.4.1   Clarified Section 3.1.4.1 Request Operation Attributes
             that a client MAY use the attribute level natural
             language override (text/nameWithLanguage) redundantly in
             a request.  (Issue 1.46)

   3.1.4.2   Clarified Section 3.1.4.2 Response Operation Attributes
             that an IPP object MAY use the attribute level natural
             language override (text/nameWithLanguage) redundantly in
             a response.  (Issue 1.46)

   3.1.6     Clarified section 3.1.6:  If the Printer object supports
             the "status-message" operation attribute, it NEED NOT
             return a status message for the following error status
             codes:  'client-error-bad-request', 'client-error-
             charset-not-supported', 'server-error-internal-error',
             'server-error-operation-not-supported', and 'server-
             error-version-not-supported'.

   3.2.1.1   Clarified that if a client is not supplying any Job
             Template attributes in a request, the client SHOULD omit
             Group 2 rather than sending an empty group.  However, a
             Printer object MUST be able to accept an empty group.
             This makes [RFC2566] agree with [RFC2565].  (Issue 1.16)

   3.2.1.2,  Clarified that if an IPP object is not returning any
   3.2.5.2,  Unsupported Attributes in a response, the IPP object
   3.2.6.2,  SHOULD omit Group 2 rather than sending an empty group.
   3.3.1.2,  However, a client MUST be able to accept an empty group.
   3.3.3.2,  This makes [RFC2566] agree with [RFC2565].  (Issue 1.17)
   3.3.4.2

   3.2.1.2,  Clarified that an IPP object MUST treat an unsupported
   13.1.2.2, attribute syntax supplied in a request in the same way
   13.1.4.12 as an unsupported value.  The IPP object MUST return the
             attribute, the attribute syntax, and the value in the
             Unsupported Attributes group.  (Issue 1.26)

   3.2.5.2,  Clarified for Get-Printer-Attributes, Get-Jobs, and Get-
   3.2.6.2,  Job-Attributes that an IPP object MUST return
   3.3.4.2,  'successful-ok-ignored-or-substituted-attributes' (0x1),

   13.1.2.1, rather than 'successful-ok' (0x0), when a client
   13.1.2.2, supplies unsupported attributes as values of the
   13.1.4.12 'requested-attributes' operation attribute.  (Issue
             1.24)
             Also clarified that the response NEED NOT contain the
             "requested-attributes" operation attribute with any
             supplied values (attribute keywords) that were requested
             by the client but are not supported by the IPP object.
             (Issue 1.18)

   3.2.6.2   Deleted the job-level natural language override (NLO)
   4.1.1.2   from Section 3.2.6.2 Get-Jobs Response so that all
   4.3.24    operation responses are the same with respect to NLO.
             (Issue 1.47)

   3.3.1     Clarified that an IPP Printer that supports the Create-
             Job operation MUST handle the situation when a client
             does not supply Send-Document or Send-URI operations
             within a one- to four-minute time period.  Also
             clarified that a client MUST send documents in a multi-
             document job without undue or unbounded delay.  (Issue
             1.28)

   3.3.3     Clarified that the IPP object MUST reject a Cancel-Job
             request if the job is in 'completed', 'canceled', or
             'aborted' job states.  (Issue 1.12)

   4.1.2.3   Added this new sub-section:  it specifies that
             nameWithoutLanguage plus the implicit natural language
             matches nameWithLanguage, if the values and natural
             languages are the same.  Also added that keyword never
             matches nameWithLanguage or nameWithoutLanguage.
             Clarified that if both have countries, that the
             countries SHOULD match as well.  If either do not, then
             the country field SHOULD be ignored.  (Issues 1.33 and
             1.34)

   4.1.5     Clarified regarding the case-insensitivity of URLs to
             refer only to the RFCs that define them.  (Issue 1.10)

   4.1.11    Clarified that 'boolean' is not a full-sized integer.
             (Issue 1.38)

   4.1.15    Clarified that 'resolution' is not three full-sized
             integers.  (Issue 1.20)

   4.2.*     Clarified that standard values are keywords or enums,
             not names.  (Issue 1.49).

   4.2.4     Added the 'single-document-new-sheet' value to Section
             4.2.4 multiple-document-handling.  (Issue 1.54)

   4.4.18,   Clarified that the "document-format-default" and
   4.4.19    "document-format-supported" Printer Description
             attributes are REQUIRED to agree with the table.  (Issue
             1.4)

   4.4.21    Changed "queued-job-count" from OPTIONAL to RECOMMENDED.
             (Issue 1.14)

   4.4.28    Clarified that the implementation supplied value for the
             "multiple-operation-time-out" attribute SHOULD be
             between 30 and 240 seconds, though the implementation
             MAY allow the administrator to set values, and MAY allow
             values outside this range.  (Issue 1.28)

   5.1,      Clarified Client Conformance that if a client supports
   5.2.5     an attribute of 'text' attribute syntax, that it MUST
             support both the textWithoutLanguage and the
             textWithLanguage forms.  Same for 'name' attribute
             syntax.  Same for an IPP object (Issue 1.48)

   6.5,      Added new section to allow Attribute Groups to be
   12.8      registered as extensions for being passed in operation
             requests and responses.  (Issue 1.25)

   7.        Updated the table of text and name attributes to agree
             with Section 4.2.

   8.5       Added a new section RECOMMENDING that the Get-Jobs
             SHOULD return non-IPP jobs whether or not assigning them
             a job-id and job-uri.  Also RECOMMENDED generating, if
             possible, job-id and job-uri and supporting other IPP
             operations on foreign jobs as an implementer option.
             (Issue 1.32)

   9.        Updated document references.

   13.1.4.14 Clarified 'client-error-charset-not-supported' that
             'utf-8' must be used for any 'text' or 'name' attributes
             returned in the error response (Issue 1.19).

   13.1.5.9  Added a new error code 'server-error-job-canceled'
             (0x0508) to be returned if a job is canceled by another
             client or aborted by the IPP object while the first
             client is still sending the document data.  (Issue 1.29)

   15.3,     Moved these sections recommending operation processing
   15.4      steps to the new Implementer's Guide (informational).
             There indicated that all of the error checks are not
             required, so an IPP object MAY be forgiving and accept
             non-conforming requests.  However, a conforming client
             MUST supply requests that would pass all of the error
             checks indicated.  (Issue 1.21)

   16        Changed directory schema attributes from REQUIRED to
             RECOMMENDED.  Changed some of the OPTIONAL to
             RECOMMENDED to agree with the SLP template.  Changed the
             "charset-supported" and "natural-language-supported"
             from REQUIRED to OPTIONAL.  Recommended that the names
             be the same in a directory entry as the IPP attribute
             names. (Issue 1.53)

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