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rfc:bcp:bcp97

[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.

Bush & Narten Best Current Practice [Page 1] RFC 3967 Document Down-Ref Clarifications December 2004

 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:
  1. 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.

Bush & Narten Best Current Practice [Page 2] RFC 3967 Document Down-Ref Clarifications December 2004

    The referenced specification would likely include details about
    specific key management requirements, which transforms are
    required and which are optional, etc.
  1. In MIB documents, an IMPORTS clause by definition is a normative

reference.

  1. 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.

Bush & Narten Best Current Practice [Page 3] RFC 3967 Document Down-Ref Clarifications December 2004

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.

Bush & Narten Best Current Practice [Page 4] RFC 3967 Document Down-Ref Clarifications December 2004

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

Bush & Narten Best Current Practice [Page 5] RFC 3967 Document Down-Ref Clarifications December 2004

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.

Bush & Narten Best Current Practice [Page 6]

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.

Klensin & Hartman Best Current Practice [Page 1] RFC 4897 Normative References June 2007

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.

Klensin & Hartman Best Current Practice [Page 2] RFC 4897 Normative References June 2007

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.

Klensin & Hartman Best Current Practice [Page 3] RFC 4897 Normative References June 2007

 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.

Klensin & Hartman Best Current Practice [Page 4] RFC 4897 Normative References June 2007

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

Klensin & Hartman Best Current Practice [Page 5] RFC 4897 Normative References June 2007

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.

Klensin & Hartman Best Current Practice [Page 6]

Internet Engineering Task Force (IETF) B. Leiba Request for Comments: 8067 Huawei Technologies BCP: 97 January 2017 Updates: 3967 Category: Best Current Practice ISSN: 2070-1721

  Updating When Standards Track Documents May Refer Normatively to
                     Documents at a Lower Level

Abstract

 RFC 3967 specifies a process for allowing normative references to
 documents at lower maturity levels ("downrefs"), which involves
 calling out the downref explicitly in the Last Call notice.  That
 requirement has proven to be unnecessarily strict, and this document
 updates RFC 3967, allowing the IESG more flexibility in accepting
 downrefs in Standards Track documents.

Status of This Memo

 This memo documents an Internet Best Current Practice.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It has been approved for publication by the Internet
 Engineering Steering Group (IESG).  Further information on BCPs is
 available in Section 2 of RFC 7841.
 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/rfc8067.

Copyright Notice

 Copyright (c) 2017 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.

Leiba Best Current Practice [Page 1] RFC 8067 Document Downref Update January 2017

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
 2.  The IESG's Responsibility with Respect to Downrefs  . . . . .   2
 3.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
 4.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
 Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   3

1. Introduction

 [RFC3967] notes the importance of assuring that normative references
 from Standards Track and Best Current Practice (BCP) documents are
 appropriately mature, and specifies a process for allowing normative
 references to documents at lower maturity levels ("downrefs").  That
 process starts at IETF Last Call (see Section 3 of [RFC3967]):
    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.
 Section 2 of [RFC3967] lists some conditions under which downrefs may
 make sense.  In addition to those, it has become common for working
 groups to produce foundational documents (which contain important
 information such as terminology definitions and architectural design
 and considerations) at Informational status, and those documents are
 often needed as normative references in the Standards Track protocol
 documents that follow.
 The requirement to explicitly mention the downrefs and the need for
 them in the Last Call message has proven to be unnecessarily
 restrictive and has often resulted in unnecessary repetitions of Last
 Call, with the corresponding delay and with no real benefit.

2. The IESG's Responsibility with Respect to Downrefs

 The process in RFC 3967 is hereby updated to specify that explicitly
 documenting the downward references in the Last Call message is
 strongly recommended but not required.  The responsible AD should
 still check for downrefs before sending out the Last Call notice, but
 if an undetected downref is noticed during Last Call or IESG review,
 any need to repeat the Last Call is at the discretion of the IESG.
 However, the process in RFC 3967 is not fundamentally altered: If the
 IESG decides not to repeat the Last Call, the status of the affected
 downrefs is not changed, and the process in RFC 3967 will still apply
 if those downrefs are used in the future.

Leiba Best Current Practice [Page 2] RFC 8067 Document Downref Update January 2017

 This gives the IESG the responsibility to determine the actual
 maturity level of the downward reference with respect to the document
 at hand, and to decide whether or not it is necessary to explicitly
 ask the IETF community for comments on the downref on a case-by-case
 basis.  In making that decision, the IESG should take into account
 the general discussion in RFC 3967.  The responsible AD should make
 sure that the omission is recorded as a comment in the datatracker.

3. Security Considerations

 Referencing immature protocols can have security and stability
 implications, and the IESG should take that into account when
 deciding whether re-consulting the community is useful.

4. Normative References

 [RFC3967]  Bush, R. and T. Narten, "Clarifying when Standards Track
            Documents may Refer Normatively to Documents at a Lower
            Level", BCP 97, RFC 3967, DOI 10.17487/RFC3967, December
            2004, <http://www.rfc-editor.org/info/rfc3967>.

Author's Address

 Barry Leiba
 Huawei Technologies
 Phone: +1 646 827 0648
 Email: barryleiba@computer.org
 URI:   http://internetmessagingtechnology.org/

Leiba Best Current Practice [Page 3]

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