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

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