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RFC 6117 - IANA Registration of Enumservices: Guide, Template, a


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Internet Engineering Task Force (IETF)                      B. Hoeneisen
Request for Comments: 6117                                       Ucom.ch
Obsoletes: 3761                                             A. Mayrhofer
Category: Standards Track                                        enum.at
ISSN: 2070-1721                                             J. Livingood
                                                                 Comcast
                                                              March 2011

                   IANA Registration of Enumservices:
                Guide, Template, and IANA Considerations

Abstract

   This document specifies a revision of the IANA Registration
   Guidelines for Enumservices, describes corresponding registration
   procedures, and provides a guideline for creating Enumservice
   Specifications.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6117.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Registration Requirements  . . . . . . . . . . . . . . . . . .  5
     3.1.  Functionality Requirements . . . . . . . . . . . . . . . .  5
     3.2.  Naming Requirements  . . . . . . . . . . . . . . . . . . .  5
     3.3.  Security Requirements  . . . . . . . . . . . . . . . . . .  6
     3.4.  Publication Requirements . . . . . . . . . . . . . . . . .  7
   4.  Enumservice Creation Cookbook  . . . . . . . . . . . . . . . .  7
     4.1.  General Enumservice Considerations . . . . . . . . . . . .  7
     4.2.  Classification, Type and Subtype . . . . . . . . . . . . .  9
       4.2.1.  General Type/Subtype Considerations  . . . . . . . . .  9
       4.2.2.  Protocol-Based Enumservices Class  . . . . . . . . . . 10
       4.2.3.  Application-Based Enumservice Classes  . . . . . . . . 10
       4.2.4.  Data Type-Based Enumservice Class  . . . . . . . . . . 12
       4.2.5.  Other Enumservice  . . . . . . . . . . . . . . . . . . 13
   5.  Required Sections and Information  . . . . . . . . . . . . . . 13
     5.1.  Introduction (REQUIRED)  . . . . . . . . . . . . . . . . . 13
     5.2.  IANA Registration (REQUIRED) . . . . . . . . . . . . . . . 13
       5.2.1.  Enumservice Class (<class>)  . . . . . . . . . . . . . 13
       5.2.2.  Enumservice Type (<type>)  . . . . . . . . . . . . . . 14
       5.2.3.  Enumservice Subtype (<subtype>)  . . . . . . . . . . . 14
       5.2.4.  URI Scheme(s) (<urischeme>)  . . . . . . . . . . . . . 15
       5.2.5.  Functional Specification (<functionalspec>)  . . . . . 15
       5.2.6.  Security Considerations (<security>) . . . . . . . . . 15
       5.2.7.  Intended Usage (<usage>) . . . . . . . . . . . . . . . 16
       5.2.8.  Enumservice Specification (<registrationdocs>) . . . . 16
       5.2.9.  Requesters (<requesters>)  . . . . . . . . . . . . . . 17
       5.2.10. Further Information (<additionalinfo>) . . . . . . . . 17
     5.3.  Examples (REQUIRED)  . . . . . . . . . . . . . . . . . . . 18
     5.4.  Implementation Recommendations / Notes (OPTIONAL)  . . . . 18
     5.5.  DNS Considerations (REQUIRED)  . . . . . . . . . . . . . . 18
     5.6.  Security Considerations (REQUIRED) . . . . . . . . . . . . 19
     5.7.  IANA Considerations (REQUIRED) . . . . . . . . . . . . . . 20
     5.8.  Other Sections (OPTIONAL)  . . . . . . . . . . . . . . . . 20

   6.  The Process of Registering New Enumservices  . . . . . . . . . 21
     6.1.  Step 1: Read This Document in Detail . . . . . . . . . . . 22
     6.2.  Step 2: Write and Submit Registration Document . . . . . . 22
     6.3.  Step 3: Request Comments From the IETF Community . . . . . 23
       6.3.1.  Outcome 1: No Changes Needed . . . . . . . . . . . . . 23
       6.3.2.  Outcome 2: Changes, But No Further Comments
               Requested  . . . . . . . . . . . . . . . . . . . . . . 23
       6.3.3.  Outcome 3: Changes and Further Comments Requested  . . 23
     6.4.  Step 4: Submit Registration Document to IANA . . . . . . . 24
     6.5.  Step 5: Expert Review  . . . . . . . . . . . . . . . . . . 24
       6.5.1.  Outcome 1: Experts Approve the Registration
               Document . . . . . . . . . . . . . . . . . . . . . . . 25
       6.5.2.  Outcome 2: Changes Required  . . . . . . . . . . . . . 25
       6.5.3.  Outcome 3: Experts Reject the Registration Document  . 25
     6.6.  Step 6: Publication of the Registration Document . . . . . 25
     6.7.  Step 7: Adding Enumservice to the IANA Registry  . . . . . 25
   7.  Expert Review  . . . . . . . . . . . . . . . . . . . . . . . . 26
     7.1.  Expert Selection Process . . . . . . . . . . . . . . . . . 26
     7.2.  Review Guidelines  . . . . . . . . . . . . . . . . . . . . 26
     7.3.  Appeals  . . . . . . . . . . . . . . . . . . . . . . . . . 27
   8.  Revision of Existing Enumservice Specifications  . . . . . . . 27
   9.  Extension of Existing Enumservice Specifications . . . . . . . 27
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 28
     10.1. Considerations Regarding This Document . . . . . . . . . . 28
     10.2. Enumservice Security Considerations Guideline  . . . . . . 28
   11. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 28
     11.1. Registry Update  . . . . . . . . . . . . . . . . . . . . . 28
     11.2. Registration Template (XML chunk)  . . . . . . . . . . . . 28
     11.3. Location . . . . . . . . . . . . . . . . . . . . . . . . . 29
     11.4. Structure  . . . . . . . . . . . . . . . . . . . . . . . . 30
     11.5. Expert Review Procedure  . . . . . . . . . . . . . . . . . 30
     11.6. Registration Procedure . . . . . . . . . . . . . . . . . . 30
       11.6.1. Published as an RFC  . . . . . . . . . . . . . . . . . 31
       11.6.2. Published as a Non-RFC . . . . . . . . . . . . . . . . 31
     11.7. Change Control . . . . . . . . . . . . . . . . . . . . . . 32
     11.8. Restrictions . . . . . . . . . . . . . . . . . . . . . . . 32
   12. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 32
   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 33
     13.1. Normative References . . . . . . . . . . . . . . . . . . . 33
     13.2. Informative References . . . . . . . . . . . . . . . . . . 34
   Appendix A.  IANA Registration Template Examples . . . . . . . . . 36
   Appendix B.  Changes from RFC 3761 . . . . . . . . . . . . . . . . 39

1.  Introduction

   E.164 Number Mapping (ENUM) [RFC6116] provides an identifier mapping
   mechanism to map E.164 numbers [ITU.E164.2005] to Uniform Resource
   Identifiers (URIs) [RFC3986] using the Domain Name System (DNS)
   [RFC1035].  One of the primary concepts of ENUM is the definition of
   "Enumservices", which allows for providing different URIs for
   different applications of said mapping mechanism.

   This document specifies a revision of the IANA registry for
   Enumservices, which was originally described in [RFC3761].  This
   document obsoletes Section 3 of RFC 3761 while RFC 6116 obsoletes RFC
   3761.

   The new registration processes, which are detailed in Section 6, have
   been specifically designed to be decoupled from the existence of the
   ENUM working group.  Compared to RFC 3761, the main changes are as
   follows:

   o  For an Enumservice to be inserted to the IANA registry,
      "Specification Required", which implies the use of a Designated
      Expert, according to "Guidelines for Writing an IANA
      Considerations Section in RFCs" [RFC5226], are now sufficient.

   o  The IANA Registration Template has been supplemented with elements
      for "Enumservice Class" and "Enumservice Specification".

   The IETF's ENUM Working Group has encountered an unnecessary amount
   of variation in the format of Enumservice Specifications.  The ENUM
   Working Group's view of what particular information is required
   and/or recommended has also evolved, and capturing these best current
   practices is helpful in both the creation of new Enumservice
   Specifications, as well as the revision or refinement of existing
   Enumservice Specifications.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   For the purpose of this document:

   o  "Registration Document" refers to a draft specification that
      defines an Enumservice and proposes its registration following the
      procedures outlined herein.

   o  "Enumservice Specification" refers to a Registration Document that
      has been approved by the experts and published according to
      "Specification Required" as defined in [RFC5226].

3.  Registration Requirements

   As specified in the Augmented Backus-Naur Form (ABNF, [RFC5234])
   found in Section 3.4.3 of [RFC6116], an Enumservice is made up of
   Types and Subtypes.  For any given Type, the allowable Subtypes (if
   any) must be defined in the Enumservice Specification.  There is
   currently no concept of a registered Subtype outside the scope of a
   given Type.

   While the combination of each Type and all of its Subtypes
   constitutes the allowed values for the "Enumservice" field, it is not
   sufficient to just list their allowed values.  To allow for
   interoperability, a complete Enumservice Specification MUST document
   the semantics of the Type and Subtype values to be registered, and
   MUST contain all sections listed in Section 5 of this document.

   Furthermore, in order for an Enumservice to be registered, the entire
   Registration Document requires approval by the experts according to
   "Specification Required", which implies the use of a Designated
   Expert, as set out in "Guidelines for Writing an IANA Considerations
   Section in RFCs" [RFC5226] and Section 7.2 of this document.

   All Enumservice Specifications are expected to conform also to
   various requirements laid out in the following sections.

3.1.  Functionality Requirements

   A registered Enumservice must be able to function as a selection
   mechanism for choosing one Naming Authority Pointer (NAPTR) [RFC3403]
   DNS Resource Record (RR) from a set of such RRs.  That means the
   Enumservice Specification MUST define how to use the NAPTR RR and the
   URI(s) the NAPTR RR resolves to.

   Specifically, a registered Enumservice MUST specify the URI Scheme(s)
   that may be used for the Enumservice, and, when needed, other
   information that will have to be transferred into the URI resolution
   process itself.

3.2.  Naming Requirements

   The name of an Enumservice MUST be unique in order to be useful as a
   selection criteria:

   o  The Type MUST be unique.

   o  The Subtype (being dependent on the Type) MUST be unique within a
      given Type.

   Types and Subtypes MUST conform to the ABNF specified in Section
   3.4.3 of [RFC6116].

   The ABNF specified in Section 3.4.3 of [RFC6116] allows the "-"
   (dash) character for Types and Subtypes.  To avoid confusion with
   possible future prefixes, a "-" MUST NOT be used as the first nor as
   the second character of a Type nor a Subtype.  Furthermore, a "-"
   MUST NOT be used as the last character of a Type nor a Subtype.  In
   addition, Types and Subtypes are case insensitive and SHOULD be
   specified in lowercase letters.

   Note: The legacy IANA registry of Enumservices contains Type and
   Subtype strings with uppercase letters.  Implementors could be
   tempted to refuse handling uppercase Type or Subtype strings, which
   could negatively affect interoperability.

   To avoid confusion with Enumservice fields using a deprecated
   (obsolete) syntax, Type and Subtype MUST NOT start with the string
   "e2u".

   The Subtype for one Type MAY have the same identifier as a Subtype
   for another Type, but it is not sufficient to simply reference
   another Type's Subtype.  The functionality of each Subtype MUST be
   fully specified in the context of the Type being registered.

   Section 4 contains further naming requirements.

3.3.  Security Requirements

   An analysis of security issues is REQUIRED for all registered
   Enumservices.  (This is in accordance with the basic requirements for
   all IETF protocols.)

   All descriptions of security issues MUST be as accurate and extensive
   as feasible.  In particular, a statement that there are "no security
   issues associated with this Enumservice" must not be confused with
   "the security issues associated with this Enumservice have not been
   assessed".

   There is no requirement that an Enumservice must be completely free
   of security risks.  Nevertheless, all known security risks MUST be
   identified in an Enumservice Specification.

   Some of the issues to be looked at in a security analysis of an
   Enumservice are:

   1.  Complex Enumservices may include provisions for directives that
       institute actions on a user's resources.  In many cases provision
       can be made to specify arbitrary actions in an unrestricted
       fashion which may then have devastating results (especially if
       there is a risk for a new ENUM look-up, and because of that an
       infinite loop in the overall resolution process of the E.164
       number).

   2.  Complex Enumservices may include provisions for directives that
       institute actions which, while not directly harmful, may result
       in disclosure of information that either facilitates a subsequent
       attack or else violates the users' privacy in some way.

   3.  An Enumservice might be targeted for applications that require
       some sort of security assurance but do not provide the necessary
       security mechanisms themselves.  For example, an Enumservice
       could be defined for storage of confidential security services
       information such as alarm systems or message service passcodes,
       which in turn require an external confidentiality service.

3.4.  Publication Requirements

   Enumservices Specifications MUST be published according to the
   requirements for "Specification Required" set out in "Guidelines for
   Writing an IANA Considerations Section in RFCs" [RFC5226].  RFCs
   fulfill these requirements.  Therefore, it is strongly RECOMMENDED to
   publish Enumservice Specifications as RFCs.

   In case the Enumservice Specification is not published as an RFC,
   sufficient information that allows unique identification of the
   Enumservice Specification MUST be provided.

4.  Enumservice Creation Cookbook

4.1.  General Enumservice Considerations

   ENUM is an extremely flexible identifier mapping mechanism, using
   E.164 (phone) numbers as input identifiers, and returning URIs as
   output identifiers.  Because of this flexibility, almost every use
   case for ENUM could be implemented in several ways.

   Section 2 of "Guidelines for Writing an IANA  Considerations Section
   in RFCs" [RFC5226] provides motivation for why management of a
   namespace might be necessary.  Even though the namespace for
   Enumservices is rather large (up to 32 alphanumeric characters),
   there are reasons to manage this in accordance with Section 2 of
   [RFC5226].  The following is a list of motivations applying to
   Enumservices:

   o  Prevent hoarding or wasting of values: Enumservice Types are not
      an opaque identifier to prevent collisions in the namespace, but
      rather identify the use of a certain technology in the context of
      ENUM.  Service Types might also be displayed to end users in
      implementations, so meaningful Type strings having a clear
      relation to the protocols and applications used are strongly
      RECOMMENDED.  Therefore, preventing hoarding, wasting, or
      "hijacking" of Enumservice Type strings is important.

   o  Sanity check to ensure sensible or necessary requests: This
      applies to Enumservices, since especially various Enumservices for
      the same purpose would reduce the chance of successful
      interoperability, and unnecessarily increase confusion among
      implementers.

   o  Delegation of namespace portions: Theoretically, the Type and/or
      Subtype structure of Enumservices would allow for delegations of
      Type values, and self-supporting management of Subtype values by a
      delegate within the Type value.  Such delegates could, for
      example, be other standardization bodies.  However, this would
      require clear policies regarding publication and use of such
      Subtypes.  Delegation of Enumservice namespace portions is
      therefore currently not supported.

   o  Interoperability: Since the benefit of an Enumservice rises with
      the number of supporting clients, the registration and use of
      several services for a similar or identical purpose clearly
      reduces interoperability.  Operational circumstances suggest to
      keep the space occupied by all services published in the NAPTR
      RRSet at any owner in the e164.arpa domain bounded.  Registration
      of nearly identical services and subsequent competing or parallel
      use could easily increase the DNS operational complexity.

   Generally, before commencing work on a new Enumservice registration,
   the following should be considered:

   o  Is there an existing Enumservice that could fulfill the desired
      functionality without overloading it?  Check the IANA Enumservice
      Registry at <http://www.iana.org/assignments/enum-services>.

   o  Is there work in progress, or previous work, on a similar
      Enumservice?  Check the <enum@ietf.org> mailing list archives at
      <http://www.ietf.org/mail-archive/web/enum/index.html>, and search
      the Internet-Drafts Archive at <http://tools.ietf.org/>.  Some
      Internet-Drafts may have expired and no longer be available in the
      Internet-Drafts Archive, or some work on Enumservices may have
      been considered outside the IETF; therefore, we also recommend a
      web search.

   o  Section 4.2 provides three general categories for Enumservice
      classification.  In some cases, there might be several options for
      designing an Enumservice.  For example, a mapping service using
      HTTP could be considered a "protocol Type" Enumservice (using HTTP
      as the protocol), while it could also be viewed as an "application
      Type" Enumservice, with the application providing access to
      mapping services.  In such a case where several options are
      available, defining use cases before commencing work on the
      Enumservice itself might be useful before making a decision on
      which aspect of the Enumservice is more important.

4.2.  Classification, Type and Subtype

   Because of their flexibility, Enumservices can be and are used in a
   lot of different ways.  This section contains a classification of
   Enumservices, and provides guidance for choosing suitable Type and
   Subtype strings for each individual Enumservice Class.

   The Classification of each Enumservice MUST be listed in the
   Registration Document (see Section 5.2).  If the Enumservice cannot
   be assigned to one of the classes outlined below, the Registration
   Document MUST contain a section on the difficulties encountered while
   trying to classify the service to help the experts in their decision.

4.2.1.  General Type/Subtype Considerations

   To avoid confusion, the name of a URI Scheme MUST NOT be used as a
   Type string for an Enumservice that is not specifically about the
   respective protocol or URI Scheme.  For example, the Type string
   "imap" would be inadequate for use in an Enumservice about "Internet
   mapping" services, because it corresponds to an existing URI Scheme /
   protocol for something different.

   If Subtypes are defined, the minimum number SHOULD be two (including
   the empty Subtype, if defined).  The choice of just one possible
   Subtype for a given Type does not add any information when selecting
   an ENUM record, and hence can be left out completely.  However,
   potential future expansion of a Type towards several Subtypes may
   justify the use of Subtypes, even in the case that just one is
   currently defined, as noted in Section 9.

   It is perfectly legal under a certain Type to mix the Enumservice
   without a Subtype (empty Subtype) with Enumservices containing a
   Subtype.  In that case, however, the Enumservice with an empty
   Subtype SHOULD be specified to reflect the base service, while the
   other Enumservices SHOULD be specified to reflect variants.

4.2.2.  Protocol-Based Enumservices Class

   Such an Enumservice indicates that an interaction using the named
   protocol will result for use of this NAPTR.  The expected behavior of
   a system using this Enumservice MUST be clear from the protocol.

   A good indication that an Enumservice belongs to this Class is the
   fact that a client does not need to understand the actual application
   to make use of an instance of this Enumservice.

   Examples of such Enumservices include "xmpp" [RFC4979] and "sip"
   [RFC3764].

4.2.2.1.  Protocol-Based Enumservice "Type" Strings

   A protocol-based Enumservice SHOULD use the lowercase name of the
   protocol as its Type string.  Names as registered in the IANA Port
   Number Registry (<http://www.iana.org/assignments/port-numbers>,
   defined in Section 8 and 9 of [RFC2780]) are preferred.

4.2.2.2.  Protocol-Based Enumservice "Subtype" Strings

   Where there is a single URI Scheme associated with this protocol, a
   Subtype SHOULD NOT be specified for the Enumservice.

   Where there are a number of different URI Schemes associated with
   this protocol, the Enumservice Specification MAY use the empty
   Subtype for all URI Schemes that it specifies as mandatory to
   implement.  For each URI Scheme that is not mandatory to implement, a
   distinct Subtype string MUST be used.

   If Subtypes are defined, it is RECOMMENDED to use the URI Scheme name
   as the Subtype string.

4.2.3.  Application-Based Enumservice Classes

   Application-based Enumservices are used when the kind of service
   intended is not fully defined by a protocol specification.  There are
   three cases here:

   o  Common Application Enumservice:

      The application reflects a kind of interaction that can be
      realized by different protocols, but where the intent of the
      publisher is the same.  From a user's perspective, there is a
      common kind of interaction -- how that interaction is implemented
      is not important.  The Enumservice Specification MUST describe the
      interaction and expected behavior in enough detail that an

      implementation can decide if this activity is one in which it can
      engage.  However, it is RECOMMENDED that the Enumservice be
      defined in a way that will allow others to use it at a later date.
      An Enumservice that defines a generalized application is preferred
      to one that has narrow use.

      An example of this flavor of Enumservice is email.  Whilst this
      might appear to be a "pure" protocol scheme, it is not.  The URI
      Scheme is 'mailto', and it does not identify the protocol used to
      offer or retrieve emails by the sender or the recipient.

      Another example is the Short Messaging Service (SMS), where the
      existence of such an Enumservice indicates that the publishing
      entity is capable of engaging in sending or receiving a message
      according to the SMS specifications.  The underlying protocol used
      and the URI Scheme for the addressable end point can differ, but
      the "user visible" interaction of sending and receiving an SMS is
      similar.

   o  Subset Enumservice:

      The application interaction reflects a subset of the interactions
      possible by use of a protocol.  Use of this Enumservice indicates
      that some options available by use of the protocol will not be
      accepted or are not possible in this case.  Any such Enumservice
      Specification MUST define the options available by use of this
      NAPTR in enough detail that an implementation can decide whether
      or not it can use this Enumservice.  Examples of this kind of
      Enumservice are "voice:tel" and "fax:tel".  In both cases, the URI
      holds a telephone number.  However, the essential feature of these
      Enumservices is that the telephone number is capable of receiving
      a voice call or of receiving a Facsimile transmission,
      respectively.  These form subsets of the interactions capable of
      using the telephone number, and so have their own Enumservices.
      These allow an end point to decide if it has the appropriate
      capability to engage in the advertised user service (a voice call
      or sending a fax) rather than just being capable of making a
      connection to such a destination address.  This is especially
      important where there is no underlying mechanism within the
      protocol to negotiate a different kind of user interaction.

   o  Ancillary Application Enumservice

      Another variant on this is the Ancillary Application.  This is one
      in which further processing (potentially using a number of
      different protocols or methods) is the intended result of using
      this Enumservice.  An example of this kind of application is the
      "pstn:tel" Enumservice.  This indicates that the NAPTR holds

      number portability data.  It implies that the client should engage
      in number portability processing using the associated URI.  Note
      that this Enumservice usually does not itself define the kind of
      interaction available using the associated URI.  That application
      is negotiated with some other "out of band" means (either through
      prior negotiation, or explicitly through the number portability
      process, or through negotiation following the selection of the
      final destination address).

4.2.3.1.  Application-Based Enumservice "Type" Strings

   It is recommended that Application-class Enumservices use the
   lowercase well-known name of the abstract application as the Type
   string.

4.2.3.2.  Application-Based Enumservice "Subtype" Strings

   It is RECOMMENDED that the URI Scheme(s) used by the application be
   used as the Subtype string(s).  Subtype strings MAY be shared between
   URI Schemes, if all the URI Schemes within the same Subtype are
   mandatory to implement.

   If it is foreseen that there is only one URI Scheme ever to be used
   with the application, the empty Subtype string MAY be used.

4.2.4.  Data Type-Based Enumservice Class

   "Data Type" Enumservices typically refer to a specific data type or
   format, which may be addressed using one or more URI Schemes and
   protocols.  Examples of such Enumservices include "vpim" [RFC4238]
   and "vcard" [RFC4969].

4.2.4.1.  Data Type-Based Enumservice "Type" Strings

   It is recommended to use the lowercase well known name of the data
   type or format name as the Type string.

4.2.4.2.  Data Type-Based Enumservice "Subtype" Strings

   It is RECOMMENDED to use the URI Schemes used to access the service
   as Subtype strings.  Subtype strings MAY be shared between URI
   Schemes, if all the URI Schemes within the same Subtype are mandatory
   to implement.

   If there is only one URI Scheme foreseen to access the data type or
   format, the empty Subtype string MAY be used.

4.2.5.  Other Enumservice

   In case an Enumservice proposal cannot be assigned to any of the
   classes mentioned above, the <class> element (Enumservice Class) in
   the IANA Registration Template (see Section 5.2) MUST be populated
   with "Other".  In that case, the Enumservice Specification MUST
   contain a section elaborating on why the Enumservice does not fit
   into the classification structure.

5.  Required Sections and Information

   There are several sections that MUST appear in an Enumservice
   Specification.  These sections are as follows, and they SHOULD be in
   the given order.

   The following terms SHOULD begin with a capital letter, whenever they
   refer to the IANA Registration:
   o  Class
   o  Type
   o  Subtype
   o  URI Scheme

5.1.  Introduction (REQUIRED)

   An introductory section MUST be included.  This section will explain,
   in plain English, the purpose and intended use of the proposed
   Enumservice registration.

   The Introduction SHOULD start with a short sentence about ENUM,
   introduce the protocol used in the Enumservice, and discuss the
   Enumservice as it refers from the E.164 number to the protocol or
   service.

5.2.  IANA Registration (REQUIRED)

   This section MUST be included in an Enumservice Specification.  Where
   a given Enumservice Type has multiple Subtypes, there MUST be a
   separate "IANA Registration" section for each Subtype.  The following
   sections list the elements that are to be used in the XML-chunk-based
   Registration Template of an "IANA Registration" section.

5.2.1.  Enumservice Class (<class>)

   This element contains the Class of the Enumservice as defined in
   Section 4.2.  Its value MUST be one of (without quotes):

   o  "Protocol-Based": The Enumservice belongs to the Protocol-based
      class as described in Section 4.2.2.

   o  "Application-Based, Common": The Enumservice is a "common" case of
      the Application-based class as described in Section 4.2.3.

   o  "Application-Based, Subset": The Enumservice belongs to the
      "subset" case of the Application-based class as described in
      Section 4.2.3.

   o  "Application-Based, Ancillary": The Enumservice is an "ancillary"
      case of the Application-based class, as described in
      Section 4.2.3.

   o  "Data Type-Based": The Enumservice belongs to the Data Type-Based
      class as described in Section 4.2.4.

   o  "Other": The majority of the functionality of the Enumservice does
      not fall into one of the classes defined.

   Class Example

      <class>Protocol-Based</class>

5.2.2.  Enumservice Type (<type>)

   The Type of the Enumservice.  All Types SHOULD be listed in lower-
   case.  The choice of Type depends on the Enumservice Class.  Please
   find further instructions in Section 4.

   Type Example

      <type>foo</type>

5.2.3.  Enumservice Subtype (<subtype>)

   The Subtype of the Enumservice.  All Subtypes SHOULD be listed in
   lower-case.  The choice of Subtype depends on the Enumservice Class.
   Should the Enumservice not utilize a Subtype, then the <subtype>
   element MUST be omitted in the IANA Registration Template.  If a
   given Enumservice Type has multiple Subtypes, then there MUST be a
   separate IANA Registration Template for each Subtype.  Please find
   further instructions in Section 4.

   Subtype Example

      <subtype>bar</subtype>

5.2.4.  URI Scheme(s) (<urischeme>)

   The URI Schemes [RFC3986] that are used with the Enumservice.  The
   selection of URI Schemes often depends on the Enumservice Class,
   Type, and/or Subtype.  A colon MUST NOT be placed after the URI
   Scheme name.  If there is more than one URI Scheme, then one
   <urischeme> element per URI scheme MUST be used in the IANA
   Registration Template.  Please find further instructions in
   Section 4.

   URI Scheme Example

      <urischeme>bar</urischeme>
      <urischeme>sbar</urischeme>

   Note: A client cannot choose a specific ENUM record in a record set
   based on the URI Scheme - the selection is only based on Type and
   Subtype, in accordance with [RFC3402].

5.2.5.  Functional Specification (<functionalspec>)

   The Functional Specification describes how the Enumservice is used in
   connection with the URI to which it resolves.

   Functional Specification Example

          <functionalspec>
            <paragraph>
              This Enumservice indicates that the resource
              identified can be addressed by the associated
              URI in order to foo the bar.
            </paragraph>
            <paragraph>
              [...]
            </paragraph>
          </functionalspec>

   Where the terms used are non-obvious, they should be defined in the
   Enumservice Specification, or a reference to an external document
   containing their definition should be provided.

5.2.6.  Security Considerations (<security>)

   A reference to the "Security Considerations" section of a given
   Enumservice Specification.

   Security Considerations Example

          <security>
            See <xref type="rfc" data="rfc4979"/>, Section 6.
          </security>

5.2.7.  Intended Usage (<usage>)

   One of the following values (without quotes):

   o  "COMMON": Indicates that the Enumservice is intended for
      widespread use on the public Internet, and that its scope is not
      limited to a certain environment.

   o  "LIMITED USE": Indicates that the Enumservice is intended for use
      on a limited scope, for example in private ENUM-like application
      scenarios.  The use case provided in the Enumservice Specification
      should describe such a scenario.

   o  "DEPRECATED": Indicates that the Enumservice has been declared
      deprecated (Section 11.7) and is not to be used in new
      deployments.  Applications SHOULD however expect to encounter
      legacy instances of this Enumservice.

   Intended Usage Example

      <usage>COMMON</usage>

5.2.8.  Enumservice Specification (<registrationdocs>)

   Reference(s) to the Document(s) containing the Enumservice
   Specification.

   Enumservice Specification Examples

      <registrationdocs>
        <xref type="rfc" data="rfc4979"/>
      </registrationdocs>

   or

      <registrationdocs>
        <xref type="rfc" data="rfc2026"/> (obsoleted by RFC 2551)
        <xref type="rfc" data="rfc2551"/>
      </registrationdocs>

   or

      <registrationdocs>
        [International Telecommunications Union,
        "Enumservice Specification for Foobar",
        ITU-F Recommendation B.193, Release 73, Mar 2009.]
      </registrationdocs>

5.2.9.  Requesters (<requesters>)

   The persons requesting the registration of the Enumservice.  Usually
   these are the authors of the Enumservice Specification.

   Requesters Example

      <requesters>
        <xref type="person" data="John_Doe"/>
      </requesters>

      [...]

      <people>
        <person id="John_Doe">
          <name>John Doe</name>
          <org>ACME Research and Development Inc.</org>
          <uri>mailto:jd@acme.example.com</uri>
          <updated>2008-11-20</updated>
        </person>
      </people>

   If there is more than one requester, there MUST be one <xref> element
   per requester in the <requesters> element, and one <person> chunk per
   requester in the <people> element.

5.2.10.  Further Information (<additionalinfo>)

   Any other information the authors deem interesting, including
   artwork.

   Further Information Example

      <additionalinfo>
        <paragraph>more info goes here</paragraph>
      </additionalinfo>

   Note: If there is no such additional information, then the
   <additionalinfo> element is omitted.

5.3.  Examples (REQUIRED)

   This section MUST show at least one example of the Enumservice being
   registered, for illustrative purposes.  The example(s) shall in no
   way limit the various forms that a given Enumservice may take, and
   this should be noted at the beginning of this section of the
   document.  The example(s) MUST show the specific formatting of the
   intended NAPTRs (according to [RFC3403] and [RFC6116]), including one
   or more NAPTR example(s), AND a brief textual description, consisting
   of one or more sentences written in plain English, explaining the
   various parts or attributes of the record(s).

   The example(s) SHOULD contain a brief description how a client
   supporting this Enumservice could behave, if that description was not
   already given in, e.g., the Introduction or the Functional
   Specification.

   The example(s) SHOULD follow any relevant IETF guidelines on the use
   of domain names, phone numbers, and other resource identifier
   examples, such as [RFC2606].

   For example:
   $ORIGIN 9.7.8.0.6.9.2.3.6.1.4.4.e164.arpa.
   @ IN NAPTR 100 10 "u" "E2U+foo:bar" "!^.*$!bar://example.com/!" .

5.4.  Implementation Recommendations / Notes (OPTIONAL)

   Recommendations that pertain to implementation and/or operations
   SHOULD be included.  Such a section is helpful to someone reading an
   Enumservice Specification and trying to understand how best to use it
   to support their network or service.

5.5.  DNS Considerations (REQUIRED)

   In case the inclusion of protocols and URI Schemes into ENUM
   specifically introduces new DNS issues, those MUST be described
   within this section.

   Such DNS issues include, but are not limited to:

   o  Assumptions about ownership or administrative control of the
      namespace.

   o  Requirement or need to use DNS wildcards.

   o  Incompatibility with DNS wildcards.

   o  Presence or absence of respective NAPTR Resource Records at
      particular levels in the DNS hierarchy (e.g., only for "full"
      E.164 numbers or wildcards only).

   o  Use of any Resource Records (especially non-NAPTR) within or
      beyond the e164.arpa namespace other than those needed to resolve
      the domain names that appear in the "replacement" URI.

   o  Potential for significant additional load on the nameserver chain
      due to use of the service, and the mitigation of such additional
      load.

   o  Mitigation of potential for DNS loops, specifically in cases where
      the result URI of an Enumservice might be used to trigger
      additional (subsequent) ENUM queries.  This applies in particular
      to Enumservices using the 'tel' URI Scheme [RFC3966] or any other
      (future) URI Scheme using (E.164) numbers.  "The ENUM Dip
      Indicator Parameter for the tel URI" [RFC4759] provides an example
      of a loop mitigation mechanism.

   Rationale: some Enumservices try to exploit side effects of the DNS
   that need to be explicitly discussed.

5.6.  Security Considerations (REQUIRED)

   A section explaining any potential security threats that are
   especially applicable to the given registration MUST be included.
   This MUST also include any information about access to Personally
   Identifiable Information (PII).

   An Enumservice Specification SHOULD NOT include general and obvious
   security recommendations, such as securing servers with strong
   password authentication.

   For additional background, please note that [RFC3552] provides
   guidance to write a good Security Considerations section.  In
   addition, [RFC6116] already outlines security considerations
   affecting ENUM as a whole.  Enumservice Specifications do not need to
   and SHOULD NOT repeat considerations already listed in that document.
   However, Enumservice Specifications SHOULD include a reference to
   that section.

   Also, ENUM refers to resources using existing URI Schemes and
   protocols.  Enumservice Specifications do not need to and SHOULD NOT
   repeat security considerations affecting those protocols and URI
   Schemes themselves.

   However, in some cases, the inclusion of those protocols and URI
   Schemes into ENUM specifically could introduce new security issues.
   In these cases, those issues or risks MUST be covered in the
   "Security Considerations" section of the Enumservice Specification.
   Authors should pay particular attention to any indirect risks that
   are associated with a proposed Enumservice, including cases where the
   proposed Enumservice could lead to the discovery or disclosure of
   Personally Identifiable Information (PII).

5.7.  IANA Considerations (REQUIRED)

   Describe the task IANA needs to fulfill to process the Enumservice
   Registration Document.

   For example:
   This document requests the IANA registration of the Enumservice with
   Type "foo" and Subtype "bar" according to the definitions in this
   document, [RFC6117], and [RFC6116].

   For example:
   This document requests an update of the IANA registration of the
   Enumservice Type "foo" with Subtype "bar", according to the
   definitions in this document, [RFC6117], and [RFC6116].  Therefore,
   in the existing IANA registration for this Enumservice, the
   <registrationdocs> element (Enumservice Specification) is enhanced by
   adding a supplementary reference that points to this document.

   For example:
   This document requests an update of the IANA registration of the
   Enumservice Type "foo" with all its Subtypes, in order to declare it
   deprecated.  Therefore, in the existing IANA registration for this
   Enumservice, the <usage> element (Intended Usage) is changed to
   "DEPRECATED", and the <registrationdocs> element (Enumservice
   Specification) is enhanced by adding a supplementary reference that
   points to this document.

5.8.  Other Sections (OPTIONAL)

   Other sections beyond those required above MAY be included in an
   Enumservice Specification.  These sections may relate to the
   specifics of the intended use of the Enumservice registration, as
   well as to any associated technical, operational, administrative, or
   other concerns.

   A use case SHOULD be included by the authors of the proposal, so that
   experts can better understand the problem the proposal seeks to solve
   (intended use of the Enumservice).  The inclusion of such a use case

   will both accelerate the Expert Review process, as well as make any
   eventual registration easier to understand and implement by other
   parties.

6.  The Process of Registering New Enumservices

   This section is an illustration of the process by which a new
   Enumservice Registration Document is submitted for review and
   comment, how such proposed Enumservices are reviewed, and how they
   are published.  This section is a non-normative description of the
   process.  The normative process is described in [RFC5226].

   Figure 1 shows what authors of a Registration Document describing an
   Enumservice must carry out before said Registration Document can be
   formally submitted to IANA for Expert Review.  Figure 2 shows the
   process from Expert Review onwards.

                     +----------------------------+
                     | Step 1: Read this document |
                     +----------------------------+
                                  |
                                  V
                   +-------------------------------+
                   | Step 2:  Write R-D and submit |
                   +-------------------------------+
                                  |
                                  V
             +--------------------------------------------+
             | Step 3:  Announce R-D and solicit feedback |<--+
             +--------------------------------------------+   |
                                  |                           |
                                  V                           |
                                 .^.                          |
                               .     .                        |
   +------------+            .  Feed-  .               +------------+
   | Update R-D |<---------<    back     >------------>| Update R-D |
   | and submit |  non-sub-  . results .   substantial | and submit |
   +------------+  stantial    . in: .     changes     +------------+
         |         changes       . .       needed
         |         needed         Y
         |                        | no changes needed
         |                        V
         |         +-----------------------------+
         +-------->| Step 4:  Submit R-D to IANA |
                   +-----------------------------+
                                  :
                                  :
                                  V

   R-D: Registration Document

                                 Figure 1

6.1.  Step 1: Read This Document in Detail

   This document, particularly in Sections 3, 4, and 5, describes all of
   the recommended and required sections, as well as requirements and
   suggestions for content of an Enumservice Specification.

6.2.  Step 2: Write and Submit Registration Document

   An Internet-Draft (or another specification as appropriate) must be
   written and made publicly available (submitted).  The Registration
   Document shall follow the guidelines according to Sections 4 and 5 of

   this document.  The Review Guidelines for experts are defined in
   Section 7.2.

6.3.  Step 3: Request Comments From the IETF Community

   The authors shall send an email to <enum@ietf.org>, in which comments
   on the Registration Document are requested.  A proper public
   reference (a URL is recommended) to the Registration Document must be
   included in this email.

   Note: The ENUM WG mailing list <enum@ietf.org> will be kept open
   after conclusion of the ENUM WG.

   The authors should allow a reasonable period of time to elapse, such
   as two to four weeks, in order to collect any feedback.  The authors
   then consider whether or not to take any of those comments into
   account, by making changes to the Registration Document and
   submitting a revision, or otherwise proceeding.  The following
   outcomes are open to the authors.  The choice of path is left to the
   authors' judgement.

   Note: Whatever the outcome is, the experts performing the Expert
   Review later in the process are not bound to any decision during this
   phase.

6.3.1.  Outcome 1: No Changes Needed

   No changes to the Registration Document are made, and the authors
   proceed to Step 4 below.

   This outcome is recommended when the feedback received does not lead
   to a new revision of the Registration Document.

6.3.2.  Outcome 2: Changes, But No Further Comments Requested

   The authors update the Registration Document and is/are confident
   that all issues are resolved and do not require further discussion.
   The authors proceed to Step 4 below.

   This outcome is recommended when minor objections have been raised,
   or minor changes have been suggested.

6.3.3.  Outcome 3: Changes and Further Comments Requested

   The authors update and submit the Registration Document, and proceed
   to Step 3 above, which involves sending another email to
   <enum@ietf.org> to request additional comments for the updated
   version.

   This outcome is recommended when substantial objections have been
   raised, or substantial changes have been suggested.

6.4.  Step 4: Submit Registration Document to IANA

   The authors submit the Registration Document to IANA (using the
   <http://www.iana.org/> website) for Expert Review.

                                  :
                                  :
                                  V
                       +-----------------------+
                       | Step 5: Expert Review |<-------------+
                       +-----------------------+              |
                                  |                           |
                                  V                           |
                                 .^.                          |
                               .     .                        |
     .---------.             .  Expert .               +------------+
    ( Bad luck! )<-------- <    Review   >------------>| Update R-D |
     `---------'   experts   . results .   changes     | and submit |
                   reject      . in: .     required    +------------+
                                 . .
                                  Y
                                  | experts approve
                                  V
                +-----------------------------------+
                | Step 6: Publication of R-D        |
                +-----------------------------------+
                                  |
                                  V
           +---------------------------------------------+
           | Step 7: Adding Enumservice to IANA Registry |
           +---------------------------------------------+

   R-D: Registration Document

                                 Figure 2

6.5.  Step 5: Expert Review

   IANA will take care of the "Expert Review" according to [RFC5226].
   The Expert Review guidelines are outlined in Section 7.2 of this
   document.  The authors must be prepared for further interaction with
   IANA and the experts.

6.5.1.  Outcome 1: Experts Approve the Registration Document

   No (more) changes to the Registration Document are made.  IANA will
   inform the authors, who then will proceed to Step 6 below.

6.5.2.  Outcome 2: Changes Required

   The experts might require changes before they can approve the
   Registration Document.  The authors update and submit the
   Registration Document.  The authors inform the experts about the
   available update, who then continue the Expert Review Process.

6.5.3.  Outcome 3: Experts Reject the Registration Document

   The expert might reject the Registration, which means the Expert
   Review process is discontinued.

6.6.  Step 6: Publication of the Registration Document

   The authors are responsible for ensuring that the Registration
   Document is published according to "Specification Required" as
   defined in [RFC5226].

   As set out in Section 3.4 it is strongly RECOMMENDED that Enumservice
   Specifications be published RFCs.  As to every RFC, the normal IETF
   publication process applies (see [Instructions2authors]); i.e., the
   Registration Document is submitted in the form of an Internet Draft
   (e.g. via an IETF Working Group or a sponsoring Area Director).
   [Instructions2authors] also contains an option to publish an RFC as
   'Independent Submission', which is further described in "Independent
   Submissions to the RFC Editor" [RFC4846].

6.7.  Step 7: Adding Enumservice to the IANA Registry

   In cases where the Registration Document is to be published as an
   RFC, the RFC publication process ensures that IANA will add the
   Enumservice to the registry.

   In cases where the Registration Document is to be published in a
   specification other than RFC, the authors must inform IANA, as soon
   as the Enumservice Specification has been published according to
   "Specification Required" as defined in [RFC5226].  The
   <registrationdocs> element in the IANA Registration Template must
   contain an unambiguous reference to the Enumservice Specification
   (see also Section 5.2).  In addition, the authors must provide IANA
   with a stable URL to the Enumservice Specification, in order that
   IANA may obtain the information included in the Enumservice
   Specification.  IANA will then add the Enumservice to the registry.

7.  Expert Review

7.1.  Expert Selection Process

   According to Section 3.2 of [RFC5226], experts are appointed by the
   IESG.  The IESG is responsible for ensuring that there is always a
   sufficient pool of experts available.

7.2.  Review Guidelines

   Generally, the "Expert Review" process of an Enumservice follows the
   guidelines documented in Section 3.3 of "Guidelines for Writing an
   IANA Considerations Section in RFCs" [RFC5226].  Note that RFC 5226
   says 'The review may be wide or narrow, depending on the situation
   and the judgment of the designated expert'.  Therefore, the following
   list should be considered a guideline, rather than a binding list.

   In case of conflicts between [RFC5226] and the guidelines in this
   section, [RFC5226] remains authoritative.

   The expert evaluates the criteria as set out in [RFC5226], and should
   additionally consider the following:

   o  Verify conformance with the ENUM specification [RFC6116].

   o  Verify that the requirements set out in this document (Sections 3
      and 5) are met.  This includes checking for completeness and
      whether all the aspects described in Sections 3 and 5 are
      sufficiently addressed.

   o  If a use case is provided, the experts should verify whether the
      proposed Enumservice does actually match the use case.  The
      experts should also determine whether the use case could be
      covered by an existing Enumservice.

   o  Verify that the Enumservice proposed cannot be confused with
      identical (or similar) other Enumservices already registered.

   o  If the Enumservice is classified according to Section 4.2, the
      experts must verify that the principles of the Class in question
      are followed.

   o  In case the Enumservice is not classified, the experts must verify
      whether a convincing reason for the deviation is provided in the
      Registration Document.

   o  Investigate whether the proposed Enumservice has any negative side
      effects on existing clients and infrastructure, particularly the
      DNS.

   o  If the output of processing an Enumservice might be used for input
      to more ENUM processing (especially services returning 'tel'
      URIs), the experts should verify that the authors have adequately
      addressed the issue of potential query loops.

7.3.  Appeals

   Appeals of Expert Review decisions follow the process described in
   Section 7 of [RFC5226] and Section 6.5 of [RFC2026].

8.  Revision of Existing Enumservice Specifications

   Many Enumservice registrations, published via IETF RFCs, already
   exist at the time of the development of this document.  These
   existing Enumservice Specifications MAY be revised to comply with the
   specifications contained herein.  All revisions of Enumservice
   Specifications MUST be compliant with the specifications contained
   herein.

   Note: Enumservice Specifications updated only by [RFC6118] are not
   compliant with the specifications contained herein!

9.  Extension of Existing Enumservice Specifications

   There are cases where it is more sensible to extend an existing
   Enumservice registration rather than propose a new one.  Such cases
   include adding a new Subtype to an existing Type.  Depending on the
   nature of the extension, the original Enumservice Specification needs
   to be extended (Updates) or replaced (Obsoletes) [RFC2223].
   Specifically, an update is appropriate when a new Subtype is being
   added without changes to the existing repertoire.  A replacement is
   needed if there is a change to the default, or changes to the
   assumptions of URI support in clients.

   Any Enumservice Specifications for existing Enumservices that are
   extended MUST comply with the specifications contained herein.  As a
   consequence, revisions of existing Enumservice Specifications may be
   required according to Section 8.

10.  Security Considerations

10.1.  Considerations Regarding This Document

   Since this document does not introduce any new technology, protocol,
   or Enumservice Specification, there are no specific security issues
   to be considered for this document.  However, as this is a guide to
   authors of new Enumservice Specifications, the next section should be
   considered closely by authors and experts.

10.2.  Enumservice Security Considerations Guideline

   Guidelines concerning the Security Considerations section of an
   Enumservice Specification can be found in Section 5.6.

11.  IANA Considerations

11.1.  Registry Update

   IANA updated the registry "Enumservice Registrations" as defined in
   (this) Section 11, which replaces the old mechanism as defined in
   [RFC3761].

   It is noted that the process described herein applies only to
   ordinary Enumservice registrations (i.e., the registration process of
   "X-" Enumservices is beyond the scope of this document, and as per
   [RFC6116] "P-" Enumservices will not be registered at all).

11.2.  Registration Template (XML chunk)

           <record>
             <class> <!-- Enumservice Class --> </class>
             <type> <!-- Type --> </type>
             <subtype> <!-- Subtype --> </subtype>
             <urischeme> <!-- URI Schema Name --> </urischeme>
             <urischeme> <!-- another URI Schema Name --> </urischeme>
             <functionalspec>
               <paragraph>
                 <!-- Text that explains the functionality of
                      the Enumservice to be registered -->
               </paragraph>
             </functionalspec>
             <security>
                 <!-- Security Considerations of the
                      Enumservice to be registered -->
             </security>
             <usage> <!-- COMMON, LIMITED USE, or OBSOLETE --> </usage>
             <registrationdocs>

               <!-- Change accordingly -->
               <xref type="rfc" data="rfc2551"/>
             </registrationdocs>
             <requesters>
               <!-- Change accordingly -->
               <xref type="person" data="John_Doe"/>
               <xref type="person" data="Jane_Dale"/>
             </requesters>
             <additionalinfo>
               <paragraph>
                 <!-- Text with additional information about
                      the Enumservice to be registered -->
               </paragraph>
               <artwork>
                 <!-- There can be artwork sections, too -->
                 :-)
               </artwork>
             </additionalinfo>
           </record>

          <people>
            <person id="John_Doe">
              <name> <!-- Firstname Lastname --> </name>
              <org> <!-- Organisation Name --> </org>
              <uri> <!-- mailto: or http: URI --> </uri>
              <updated> <!-- date format YYYY-MM-DD --> </updated>
            </person>
            <!-- repeat person section for each person -->
          </people>

   Authors of an Enumservice Specification are encouraged to use these
   XML chunks as a template to create the IANA Registration Template.
   Examples for the use of this template are contained in Appendix A.

11.3.  Location

   Approved Enumservice registrations are published in the IANA registry
   named "Enumservice Registrations", which is available at the
   following URI:
   <http://www.iana.org/assignments/enum-services>.

   This registry publishes representations derived from the IANA
   Registration Template as described in Section 11.2 and specified in
   Section 5.2.

   Where the Enumservice Specification is not an RFC, IANA must hold an
   escrow copy of that Enumservice Specification.  Said escrow copy will
   act as the master reference for that Enumservice registration.

11.4.  Structure

   IANA maintains the Enumservice Registry sorted in alphabetical order.
   The first sort field is Type, the second is Subtype.

   [RFC6118] updates the existing Enumservices by transforming them into
   the new XML-chunk-based IANA Registration Template (see also
   Section 8).

11.5.  Expert Review Procedure

   Whenever a Registration Document is submitted via the IANA website,
   IANA will take care of the "Expert Review" process according to
   "Guidelines for Writing an IANA Considerations Section in RFCs"
   [RFC5226].

   To prevent clashes, IANA will check whether a request with identical
   "type:subtype" (or "type" without Subtype) was submitted for Expert
   Review earlier and will inform the experts accordingly.  The experts
   are authorized to resolve clashes as they see fit.  The requesters
   may need to update their registration request before getting expert
   approval.

   Once the experts have conditionally approved the Enumservice, IANA
   will inform the authors.  This information should also include a
   reminder that (i) the authors are now responsible for publication of
   the Registration Document (see also Section 6.6) and (ii) the
   Enumservice will be added to the IANA registry only after its
   Enumservice Specification is published according to the
   "Specification Required" policy as defined in [RFC5226] (see also
   Section 6.7).

   Note: After sending the approval note to the authors, IANA has no
   further responsibilities besides keeping internal records of approved
   Registration Documents.  IANA will be involved again at registration
   of the Enumservice (see Section 11.6).

11.6.  Registration Procedure

   There is a slight difference in process depending on whether or not
   the Enumservice Specification will be published as an RFC.  The
   reason for this difference lies in the current RFC publication
   process that includes IANA interaction shortly before publication of
   an RFC.

11.6.1.  Published as an RFC

   As per the RFC publication process, IANA will receive the Enumservice
   Specification to carry out IANA actions shortly before publication of
   the RFC.  The IANA action will be to register the Enumservice, i.e.,
   add the Enumservice to the IANA "Enumservice Registrations" registry
   (see also Section 11.3).

   IANA must only add Enumservices to the Registry, if the experts have
   (conditionally) approved the corresponding Enumservice Specification.
   IANA should attempt to resolve possible conflicts arising from this
   together with the experts.  In case there are substantial changes
   between the (conditionally) approved and the to be published version,
   IANA may reject the request after consulting the experts.

   IANA must ensure that any further substantial changes the Enumservice
   Specification might undergo before final RFC publication are approved
   by the experts.

   Note: Clearly editorial changes (such as typos) or minor changes in
   purely editorial sections (such as Authors' Addresses,
   Acknowledgments, References, and alike) are not considered
   substantial.

11.6.2.  Published as a Non-RFC

   Once the authors have informed IANA about the publication, IANA must
   ensure that the requirements for "Specification Required" as defined
   in [RFC5226] are met, the reference to the specification is
   unambiguous, and the content of the Enumservice Specification is
   identical to the Registration Document as approved by the experts.
   IANA will then register the Enumservice, i.e., add the Enumservice to
   the IANA "Enumservice Registrations" registry, and make an escrow
   copy (see also Section 11.3).

   IANA must only add Enumservices to the Registry, if the experts have
   approved the corresponding Enumservice Specification.  IANA should
   attempt to resolve possible conflicts arising from this together with
   the experts.  In case there are substantial changes between the
   approved and the published version, IANA may reject the request after
   consulting the experts.

   Note: Clearly editorial changes (such as typos) or minor changes in
   purely editorial sections (such as Authors' Addresses,
   Acknowledgments, References, and alike) are not considered
   substantial.

11.7.  Change Control

   Change control of any Enumservice registrations is done by
   "Specification Required", which implies the use of a Designated
   Expert, according to [RFC5226].  Updates of Enumservice
   Specifications MUST comply with the requirements described in this
   document.  Updates are handled the same way as initial Enumservice
   registrations.

   Authorized Change Controllers are the experts and the IESG.

   Enumservice registrations must not be deleted.  An Enumservice that
   is believed to be no longer appropriate for use can be declared
   deprecated by publication of a new Enumservice Specification,
   changing the Enumservice <usage> element (Intended Usage) to
   "DEPRECATED"; such Enumservices will be clearly marked in the lists
   published by IANA.  As obsoletions are updates, they are also handled
   the same way as initial Enumservice registrations.  Alternatively,
   Enumservices may be declared deprecated by an IESG action.

11.8.  Restrictions

   As stated in Section 3.2, a "-" (dash) MUST NOT be used as the first
   nor as the second nor as the last character of a Type or a Subtype.
   Furthermore, Type or Subtype of any Enumservice MUST NOT be set to,
   nor start with, "E2U".  Any Enumservice registration requests not
   following these restrictions must be rejected by IANA, and the Expert
   Review process should not be initiated.

   Section 5.2 contains examples for Enumservice registrations.
   Therefore, IANA must not register an Enumservice with Type or Subtype
   set to "foo", "bar", or "sbar", unless the experts explicitly confirm
   an exception.

12.  Acknowledgments

   The authors would like to thank the following people who have
   provided feedback or significant contributions to the development of
   this document: Jari Arkko, Stewart Bryant, Gonzalo Camarillo,
   Lawrence Conroy, Michelle Cotton, Miguel Garcia, David Harrington,
   Alfred Hoenes, Ari Keranen, Peter Koch, Edward Lewis, Alexey
   Melnikov, Jon Peterson, Pekka Savola, and Peter Saint-Andre.

   Lawrence Conroy has provided extensive text for the Enumservice
   Classification section.

   Section 3 of [RFC3761], which was edited by Patrik Faltstrom and
   Michael Mealling, has been incorporated into this document.  Please
   see the Acknowledgments section in RFC 3761 for additional
   acknowledgments.

13.  References

13.1.  Normative References

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

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

   [RFC3402]  Mealling, M., "Dynamic Delegation Discovery System (DDDS)
              Part Two: The Algorithm", RFC 3402, October 2002.

   [RFC3403]  Mealling, M., "Dynamic Delegation Discovery System (DDDS)
              Part Three: The Domain Name System (DNS) Database",
              RFC 3403, October 2002.

   [RFC3761]  Faltstrom, P. and M. Mealling, "The E.164 to Uniform
              Resource Identifiers (URI) Dynamic Delegation Discovery
              System (DDDS) Application (ENUM)", RFC 3761, April 2004.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC6116]  Bradner, S., Conroy, L., and K. Fujiwara, "The E.164 to
              Uniform Resource Identifiers (URI) Dynamic Delegation
              Discovery System (DDDS) Application (ENUM)", RFC 6116,
              March 2011.

13.2.  Informative References

   [ITU.E164.2005]
              International Telecommunications Union, "The International
              Public Telecommunication Numbering Plan", ITU-
              T Recommendation E.164, Feb 2005.

   [Instructions2authors]
              Reynolds, J. and R. Braden, "Instructions to Request for
              Comments (RFC) Authors", RFC Editor http://
              www.rfc-editor.org/rfc-editor/instructions2authors.txt,
              August 2004.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.

   [RFC2223]  Postel, J. and J. Reynolds, "Instructions to RFC Authors",
              RFC 2223, October 1997.

   [RFC2606]  Eastlake, D. and A. Panitz, "Reserved Top Level DNS
              Names", BCP 32, RFC 2606, June 1999.

   [RFC2780]  Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
              Values In the Internet Protocol and Related Headers",
              BCP 37, RFC 2780, March 2000.

   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552,
              July 2003.

   [RFC3764]  Peterson, J., "enumservice registration for Session
              Initiation Protocol (SIP) Addresses-of-Record", RFC 3764,
              April 2004.

   [RFC3966]  Schulzrinne, H., "The tel URI for Telephone Numbers",
              RFC 3966, December 2004.

   [RFC4238]  Vaudreuil, G., "Voice Message Routing Service", RFC 4238,
              October 2005.

   [RFC4759]  Stastny, R., Shockey, R., and L. Conroy, "The ENUM Dip
              Indicator Parameter for the "tel" URI", RFC 4759,
              December 2006.

   [RFC4846]  Klensin, J. and D. Thaler, "Independent Submissions to the
              RFC Editor", RFC 4846, July 2007.

   [RFC4969]  Mayrhofer, A., "IANA Registration for vCard Enumservice",
              RFC 4969, August 2007.

   [RFC4979]  Mayrhofer, A., "IANA Registration for Enumservice 'XMPP'",
              RFC 4979, August 2007.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC6118]  Hoeneisen, B. and A. Mayrhofer, "Update of Legacy IANA
              Registrations of Enumservices", RFC 6118, March 2011.

Appendix A.  IANA Registration Template Examples

   This section contains non-normative examples of the XML-chunk-based
   IANA Registration Template:

   This is the first example:

           <record>
             <class>Protocol-Based</class>
             <type>email</type>
             <subtype>mailto</subtype>
             <urischeme>mailto</urischeme>
             <functionalspec>
               <paragraph>
                 This Enumservice indicates that the resource
                 can be addressed by the associated URI in
                 order to send an email.
               </paragraph>
             </functionalspec>
             <security>
               See <xref type="rfc" data="rfc4355"/>, Section 6.
             </security>
             <usage>COMMON</usage>
             <registrationdocs>
               <xref type="rfc" data="rfc4355"/>
             </registrationdocs>
             <requesters>
               <xref type="person" data="Lawrence_Conroy"/>
             </requesters>
           </record>

           <people>
             <person id="Lawrence_Conroy">
               <name>Lawrence Conroy</name>
               <org>Siemens Roke Manor Research</org>
               <uri>mailto:lwc@roke.co.uk</uri>
               <updated>2008-11-20</updated>
             </person>
           </people>

   This is the second example.

           <record>
             <class>Protocol-Based</class>
             <type>xmpp</type>
             <urischeme>xmpp</urischeme>
             <functionalspec>
               <paragraph>
                 This Enumservice indicates that the
                 resource identified is an XMPP entity.
               </paragraph>
             </functionalspec>
             <security>
               See <xref type="rfc" data="rfc4979"/>, Section 6.
             </security>
             <usage>COMMON</usage>
             <registrationdocs>
               <xref type="rfc" data="rfc4979"/>
             </registrationdocs>
             <requesters>
               <xref type="person" data="Alexander_Mayrhofer"/>
             </requesters>
           </record>

           <people>
             <person id="Alexander_Mayrhofer">
               <name>Alexander Mayrhofer</name>
               <org>enum.at GmbH</org>
               <uri>mailto:alexander.mayrhofer@enum.at</uri>
               <updated>2008-10-10</updated>
             </person>
           </people>

   This is the third example:

           <record>
             <class>Application-Based</class>
             <type>voicemsg</type>
             <subtype>sip</subtype>
             <urischeme>sip</urischeme>
             <functionalspec>
               <paragraph>
                 This Enumservice indicates that the resource
                 identified can be addressed by the associated
                 URI scheme in order to initiate a voice
                 communication session to a voice messaging system.
               </paragraph>
             </functionalspec>
             <security>
               See <xref type="rfc" data="rfc4279"/>, Section 3.
             </security>
             <usage>COMMON</usage>
             <registrationdocs>
               <xref type="rfc" data="rfc4279"/>
             </registrationdocs>
             <requesters>
               <xref type="person" data="Jason_Livingood"/>
               <xref type="person" data="Donald_Troshynski"/>
             </requesters>
             <additionalinfo>
               <paragraph>
                 Implementers should review a non-exclusive list of
                 examples in <xref type="rfc" data="rfc4279"/>,
                 Section 7.
               </paragraph>
             </additionalinfo>
           </record>

           <people>
             <person id="Jason_Livingood">
               <name>Jason Livingood</name>
               <org>Comcast Cable Communications</org>
               <uri>mailto:jason_livingood@cable.comcast.com</uri>
               <updated>2008-11-20</updated>
             </person>

             <person id="Donald_Troshynski">
               <name>Donald Troshynski</name>
               <org>Acme Packet</org>
               <uri>mailto:dtroshynski@acmepacket.com</uri>
               <updated>2008-11-20</updated>
             </person>
           </people>

   In the third IANA Registration Template example above, the "voicemsg"
   Enumservice is used.  This Enumservice actually has several Subtypes,
   and one of those is shown in the example.  For each Subtype, an
   individual Registration Template must be submitted to IANA, so that
   an Enumservice with several Subtypes will have several corresponding
   IANA Registration Templates.  This is to avoid any ambiguity of the
   relation between <subtype> and <urischeme> elements.

Appendix B.  Changes from RFC 3761

   This section lists the changes applied to the Enumservice
   registration process and the IANA registry definition, compared to
   RFC 3761.

   o  While RFC 3761 required "Standards track or Experimental" RFCs for
      an Enumservice to be registered, this document mandates
      "Specification Required", which implies the use of a Designated
      Expert.

   o  This document defines the classification of Enumservices.  The
      IANA Registration Template has been complemented to contain a
      <class> element (Enumservice Class).

   o  A new element <registrationdocs> (Enumservice Specification) has
      been added to the IANA Registration Template.

   o  The former field "Any other information that the author deems
      interesting" of the IANA Registration Template turned into the
      <additionalinfo> element (Further Information).

   o  The Enumservice "Name" field has been removed from the IANA
      Registration Template.

   o  The Registration Template is now a chunk of XML data, reflecting
      IANA's recent work to convert registries to XML.

Authors' Addresses

   Bernie Hoeneisen
   Ucom Standards Track Solutions GmbH
   CH-8000 Zuerich
   Switzerland

   Phone: +41 44 500 52 44
   EMail: bernie@ietf.hoeneisen.ch (bernhard.hoeneisen AT ucom.ch)
   URI:   http://www.ucom.ch/

   Alexander Mayrhofer
   enum.at GmbH
   Karlsplatz 1/9
   Wien  A-1010
   Austria

   Phone: +43 1 5056416 34
   EMail: alexander.mayrhofer@enum.at
   URI:   http://www.enum.at/

   Jason Livingood
   Comcast Cable Communications
   One Comcast Center
   1701 John F. Kennedy Boulevard
   Philadelphia, PA 19103
   USA

   Phone: +1-215-286-7813
   EMail: jason_livingood@cable.comcast.com
   URI:   http://www.comcast.com/

 

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