[Note that this file is a concatenation of more than one RFC.]
Network Working Group R. Bush
Request for Comments: 3967 IIJ
BCP: 97 T. Narten
Category: Best Current Practice IBM Corporation
December 2004
Clarifying when Standards Track Documents may Refer
Normatively to Documents at a Lower Level
Status of this Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2004).
Abstract
IETF procedures generally require that a standards track RFC may not
have a normative reference to another standards track document at a
lower maturity level or to a non standards track specification (other
than specifications from other standards bodies). For example, a
standards track document may not have a normative reference to an
informational RFC. Exceptions to this rule are sometimes needed as
the IETF uses informational RFCs to describe non-IETF standards or
IETF-specific modes of use of such standards. This document
clarifies and updates the procedure used in these circumstances.
1. Introduction
The Internet Standards Process [RFC2026] Section 4.2.4 specifies the
following:
Standards track specifications normally must not depend on other
standards track specifications which are at a lower maturity level
or on non standards track specifications other than referenced
specifications from other standards bodies.
One intent is to avoid creating a perception that a standard is more
mature than it actually is.
It should also be noted that Best Current Practice documents
[RFC1818] have generally been considered similar to Standards Track
documents in terms of what they can reference. For example, a
normative reference to an Experimental RFC has been considered an
improper reference per [RFC2026].
1.1. Normative References
Within an RFC, references to other documents fall into two general
categories: "normative" and "informative". Broadly speaking, a
normative reference specifies a document that must be read to fully
understand or implement the subject matter in the new RFC, or whose
contents are effectively part of the new RFC, as its omission would
leave the new RFC incompletely specified. An informative reference
is not normative; rather, it provides only additional background
information.
An exact and precise definition of what is (and is not) a normative
reference has proven challenging in practice, as the details and
implications can be subtle. Moreover, whether a reference needs to
be normative can depend on the context in which a particular RFC is
being published in the first place. For example, in the context of
an IETF Standard, it is important that all dependent pieces be
clearly specified and available in an archival form so that there is
no disagreement over what constitutes a standard. This is not always
the case for other documents.
The rest of this section provides guidance on what might (and might
not) be considered normative in the context of the IETF standards
process.
In the IETF, it is a basic assumption that implementors must have a
clear understanding of what they need to implement in order to be
fully compliant with a standard and to be able to interoperate with
other implementations of that standard. For documents that are
referenced, any document that includes key information an implementer
needs would be normative. For example, if one needs to understand a
packet format defined in another document in order to fully implement
a specification, the reference to that format would be normative.
Likewise, if a reference to a required algorithm is made, the
reference would be normative.
Some specific examples:
- If a protocol relies on IPsec to provide security, one cannot
fully implement the protocol unless the specification for IPsec is
available; hence, the reference would be normative.
The referenced specification would likely include details about
specific key management requirements, which transforms are
required and which are optional, etc.
- In MIB documents, an IMPORTS clause by definition is a normative
reference.
- When a reference to an example is made, such a reference need not
be normative. For example, text such as "an algorithm such as the
one specified in [RFCxxxx] would be acceptable" indicates an
informative reference, since that cited algorithm is just one of
several possible algorithms that could be used.
2. The Need for Downward References
There are a number of circumstances in which an IETF document may
need to make a normative reference to a document at a lower maturity
level, but such a reference conflicts with Section 4.2.4 of
[RFC2026]. For example:
o A standards track document may need to refer to a protocol or
algorithm developed by an external body but modified, adapted, or
profiled by an IETF informational RFC, for example, MD5 [RFC1321]
and HMAC [RFC2104]. Note that this does not override the IETF's
duty to see that the specification is indeed sufficiently clear to
enable creation of interoperable implementations.
o A standards document may need to refer to a proprietary protocol,
and the IETF normally documents proprietary protocols using
informational RFCs.
o A migration or co-existence document may need to define a
standards track mechanism for migration from, and/or co-existence
with, an historic protocol, a proprietary protocol, or possibly a
non-standards track protocol.
o There are exceptional procedural or legal reasons that force the
target of the normative reference to be an informational or
historical RFC or to be at a lower standards level than the
referring document.
o A BCP document may want to describe best current practices for
experimental or informational specifications.
3. The Procedure to Be Used
For Standards Track or BCP documents requiring normative reference to
documents of lower maturity, the normal IETF Last Call procedure will
be issued, with the need for the downward reference explicitly
documented in the Last Call itself. Any community comments on the
appropriateness of downward references will be considered by the IESG
as part of its deliberations.
Once a specific down reference to a particular document has been
accepted by the community (e.g., has been mentioned in several Last
Calls), an Area Director may waive subsequent notices in the Last
Call of down references to it. This should only occur when the same
document (and version) are being referenced and when the AD believes
that the document's use is an accepted part of the community's
understanding of the relevant technical area. For example, the use
of MD5 [RFC1321] and HMAC [RFC2104] is well known among
cryptographers.
This procedure should not be used if the proper step is to move the
document to which the reference is being made into the appropriate
category. It is not intended as an easy way out of normal process.
Rather, the procedure is intended for dealing with specific cases
where putting particular documents into the required category is
problematic and unlikely ever to happen.
4. Security Considerations
This document is not known to create any new vulnerabilities for the
Internet. On the other hand, inappropriate or excessive use of the
process might be considered a downgrade attack on the quality of IETF
standards or, worse, on the rigorous review of security aspects of
standards.
5. Acknowledgments
This document is the result of discussion within the IESG, with
particular contribution by Harald Alvestrand, Steve Bellovin, Scott
Bradner, Ned Freed, Allison Mankin, Jeff Schiller, and Bert Wijnen.
6. References
6.1. Normative References
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
6.2. Informative References
[RFC1818] Postel, J., Li, T., and Y. Rekhter, "Best Current
Practices", BCP 1, RFC 1818, August 1995.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC:
Keyed-Hashing for Message Authentication", RFC 2104,
February 1997.
7. Authors' Addresses
Randy Bush
IIJ
5147 Crystal Springs
Bainbridge Island, WA 98110
US
Phone: +1 206 780 0431
EMail: randy@psg.com
URI: http://psg.com/~randy/
Thomas Narten
IBM Corporation
P.O. Box 12195
Research Triangle Park, NC 27709-2195
US
Phone: +1 919 254 7798
EMail: narten@us.ibm.com
8. Full Copyright Statement
Copyright (C) The Internet Society (2004).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and at www.rfc-editor.org, and except as set
forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the ISOC's procedures with respect to rights in ISOC Documents can
be found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Network Working Group J. Klensin
Request for Comments: 4897
BCP: 97 S. Hartman
Updates: 3967 MIT
Category: Best Current Practice June 2007
Handling Normative References to Standards-Track Documents
Status of This Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
The Internet Engineering Task Force (IETF) and Request for Comments
(RFC) Editor have a long-standing rule that a document at a given
maturity level cannot be published until all of the documents that it
references as normative are at that maturity level or higher. This
rule has sometimes resulted in very long publication delays for
documents and some claims that it was a major obstruction to
advancing documents in maturity level. The IETF agreed on a way to
bypass this rule with RFC 3967. This document describes a simpler
procedure for downward references to Standards-Track and Best Current
Practice (BCP) documents, namely "note and move on". The procedure
in RFC 3967 still applies for downward references to other classes of
documents. In both cases, annotations should be added to such
References.
Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Normative Reference Rule ........................................3
3.1. Source Documents Not Yet Processed by the IESG .............3
3.2. Documents Already in the RFC Editor Queue ..................4
4. Target Documents Not on the Standards Track .....................4
5. Target Documents that Can Be Referenced This Way ................4
6. Security Considerations .........................................5
7. Acknowledgements ................................................5
8. Normative References ............................................5
1. Introduction
The IETF and RFC Editor have a long-standing rule (see, e.g., RFC
2026, Section 4.2.4 [RFC2026] and the extended discussion in RFC 3967
[RFC3967]) that a document at a given maturity level cannot be
published until all of the documents to which it makes a normative
reference are at that maturity level or higher. This rule has
sometimes resulted in very long publication delays for documents and
some claims that it was a major obstruction to advancing documents in
maturity level. Recognizing the problems that this rule sometimes
caused, RFC 3967 established an exception procedure for normative
downward references under some specific circumstances. Perhaps
because of its fairly stringent requirements, RFC 3967 has not proven
adequate either to clear the backlog of documents awaiting upgraded
documents or to prevent additional documents from joining that queue.
This document replaces the long-standing rule for downward references
to Standards-Track documents (including BCPs) that are already
published. For normative references to Standards-Track and BCP
documents, that rule was to hold the newer, referencing, document
until the referenced ones could be brought to the appropriate
maturity level. It is now possible, following procedures described
below, to simply note the downward normative reference and move on.
This document also updates RFC 3967. When downward references from a
source document are approved under the procedure specified in that
specification, we recommend that the references in the approved
(source) document be annotated in the same way as references approved
under this rule.
2. Terminology
A reference involves two documents, the one in which the reference is
embedded and the document referenced. Where needed for clarity,
these documents are referred to as the "source document" and "target
document", respectively.
The term "Standards-Track document", as used in this specification,
is assumed to include BCPs but not Informational or Experimental
documents of any variety or origin.
3. Normative Reference Rule
This document specifies an alternative to holding source documents
until all target documents referenced normatively are upgraded or by
applying the procedure of RFC 3967.
3.1. Source Documents Not Yet Processed by the IESG
An author or editor who requires a normative downward reference to a
Standards-Track RFC uses the following very simple procedure:
o The reference text (i.e., in the "Normative References" section of
the source document) is written as usual.
o A note is included in the reference text that indicates that the
reference is to a target document of a lower maturity level, that
some caution should be used since it may be less stable than the
document from which it is being referenced, and, optionally,
explaining why the downward reference is appropriate.
The Internet Engineering Steering Group (IESG) may, at its
discretion, specify the exact text to be used, establish procedures
regarding the text to use, or give guidance on this text. When
establishing procedures, the IESG should seek appropriate community
review.
These annotations are part of the source document. If members of the
community consider either the downward reference or the annotation
text to be inappropriate, those issues can be raised at any time
during the document life cycle, just as with any other text in the
document. There is no separate review of these references.
With appropriate community review, the IESG may establish procedures
for when normative downward references should delay a document and
when downward references should be noted. Absent specific guidance,
authors and reviewers should use their best judgment. It is assumed
that, in a significant majority of cases, noting a downward reference
is preferable to delaying publication.
At the option of the author, similar notes may be attached to non-
normative references.
3.2. Documents Already in the RFC Editor Queue
The IESG may, at its discretion, specify a procedure to be applied to
source documents that are already in the RFC Editor queue, awaiting
target referenced documents. The IESG should encourage authors with
documents in the RFC Editor queue awaiting downward references to
Standards-Track RFCs to evaluate whether this new rule is appropriate
for their documents. If authors believe that adding an annotation
and releasing the document is the best way forward, then the IESG
should ensure that appropriate review is conducted and, if that
review agrees with that of the authors' evaluation, allow the
annotations to be added. The IESG will announce its decision via the
normal Protocol-Action or Document-Action mechanisms.
4. Target Documents Not on the Standards Track
In the case of a normative reference to a document not on the
standards track that is approved under the procedures defined in RFC
3967, the annotation described in Section 3.1 or the retrospective
annotation described in Section 3.2, SHOULD be added to the reference
unless the IESG, after consideration of Last Call input, concludes it
is inappropriate.
5. Target Documents that Can Be Referenced This Way
The "downward reference by annotation" model specified here is
applicable only to published Standards-Track RFCs at lower maturity
levels.
Obviously, such downward references are part of the relevant source
document at IETF Last Call and subject to comments from the
community.
Advancing documents, when appropriate, is still considered preferable
to the use of either this procedure or the one specified in RFC 3967.
This specification does not impose a specific test or requirement to
determine appropriateness. This is partially because it would be
impossible to do so for the general case, but more so because the
intention is to permit the IESG and the community to balance the
importance of getting a source document published against the time
and difficulty associated with upgrading a target document. That
requirement is intended to be less stringent than the one of RFC
3967.
6. Security Considerations
This document specifies an IETF procedure. It is not believed to
raise any security issues although, in principle, relaxing the
normative downward reference rules for references associated with
security mechanisms could make a specification less stable and hence
less secure.
7. Acknowledgements
This proposal was suggested by a comment by Spencer Dawkins and many
complaints about the negative impact of the current rules. The
author is unsure about the validity of some of those complaints; the
proposal is, in part, a way to test the validity question. Spencer
also provided helpful comments on a preliminary version. It was
revised in response to extensive discussion in the IESG and benefited
significantly by comments from Brian Carpenter.
8. Normative References
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
[RFC3967] Bush, R. and T. Narten, "Clarifying when Standards Track
Documents may Refer Normatively to Documents at a Lower
Level", BCP 97, RFC 3967, December 2004.
Authors' Addresses
John C Klensin
1770 Massachusetts Ave, #322
Cambridge, MA 02140
USA
Phone: +1 617 491 5735
EMail: john-ietf@jck.com
Sam Hartman
Massachusetts Institute of Technology
77 Massachusetts Ave
Cambridge, MA 02139
USA
EMail: hartmans-ietf@mit.edu
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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