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Versions: (RFC 5226) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 RFC 8126

Network Working Group                                          M. Cotton
Internet-Draft                                                     ICANN
BCP: 26                                                         B. Leiba
Obsoletes: 5226 (if approved)                        Huawei Technologies
Intended status: Best Current Practice                         T. Narten
Expires: December 5, 2014                                IBM Corporation
                                                            June 3, 2014


     Guidelines for Writing an IANA Considerations Section in RFCs
                   draft-leiba-cotton-iana-5226bis-05

Abstract

   Many protocols make use of points of extensibility that use constants
   to identify various protocol parameters.  To ensure that the values
   used in these fields do not have conflicting uses, and to promote
   interoperability, their allocation is often coordinated by a central
   authority.  For IETF protocols, that role is filled by the Internet
   Assigned Numbers Authority (IANA).

   To make assignments in a given namespace prudently, IANA needs
   guidance describing the conditions under which new values should be
   assigned, as well as when and how modifications to existing values
   can be made.  This document defines a framework for the documentation
   of these guidelines by specification authors, in order to assure that
   the guidance given to IANA is clear and addresses the various issues
   that are likely in the operation of a registry.

   This is the third edition, and obsoletes RFC 5226.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 5, 2014.




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Copyright Notice

   Copyright (c) 2014 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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Keep IANA Considerations for IANA . . . . . . . . . . . .   4
     1.2.  For More Information  . . . . . . . . . . . . . . . . . .   4
     1.3.  Terminology Used In This Document . . . . . . . . . . . .   5
   2.  Creating and Revising Registries  . . . . . . . . . . . . . .   5
     2.1.  Hierarchical Registry Structure . . . . . . . . . . . . .   5
     2.2.  Documentation Requirements for Registries . . . . . . . .   7
     2.3.  Defining an Appropriate Registry Policy . . . . . . . . .   9
       2.3.1.  Using the Well-Known Registration Policies  . . . . .  11
       2.3.2.  Using Multiple Policies in Combination  . . . . . . .  13
       2.3.3.  Specifying Change Control for a Registry  . . . . . .  13
     2.4.  Revising Existing Registries  . . . . . . . . . . . . . .  14
   3.  Registering New Values in an Existing Registry  . . . . . . .  14
     3.1.  Documentation Requirements for Registrations  . . . . . .  14
     3.2.  Updating Existing Registrations . . . . . . . . . . . . .  16
     3.3.  Overriding Registration Procedures  . . . . . . . . . . .  16
     3.4.  Early Allocations . . . . . . . . . . . . . . . . . . . .  17
   4.  Well-Known Registration Policies  . . . . . . . . . . . . . .  17
     4.1.  Private Use . . . . . . . . . . . . . . . . . . . . . . .  18
     4.2.  Experimental Use  . . . . . . . . . . . . . . . . . . . .  18
     4.3.  Hierarchical Allocation . . . . . . . . . . . . . . . . .  18
     4.4.  First Come First Served . . . . . . . . . . . . . . . . .  19
     4.5.  Expert Review . . . . . . . . . . . . . . . . . . . . . .  19
     4.6.  Specification Required  . . . . . . . . . . . . . . . . .  20
     4.7.  RFC Required  . . . . . . . . . . . . . . . . . . . . . .  20
     4.8.  IETF Review . . . . . . . . . . . . . . . . . . . . . . .  20
     4.9.  Standards Action  . . . . . . . . . . . . . . . . . . . .  21
     4.10. IESG Approval . . . . . . . . . . . . . . . . . . . . . .  21
   5.  Designated Experts  . . . . . . . . . . . . . . . . . . . . .  22
     5.1.  The Motivation for Designated Experts . . . . . . . . . .  22
     5.2.  The Role of the Designated Expert . . . . . . . . . . . .  23



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     5.3.  Designated Expert Reviews . . . . . . . . . . . . . . . .  24
     5.4.  Expert Reviews and the Document Lifecycle . . . . . . . .  26
   6.  Well-Known Registration Status Terminology  . . . . . . . . .  26
   7.  Documentation References in IANA Registries . . . . . . . . .  27
   8.  What to Do in "bis" Documents . . . . . . . . . . . . . . . .  27
   9.  Miscellaneous Issues  . . . . . . . . . . . . . . . . . . . .  29
     9.1.  When There Are No IANA Actions  . . . . . . . . . . . . .  29
     9.2.  Namespaces Lacking Documented Guidance  . . . . . . . . .  29
     9.3.  After-the-Fact Registrations  . . . . . . . . . . . . . .  30
     9.4.  Reclaiming Assigned Values  . . . . . . . . . . . . . . .  30
     9.5.  Contact Person vs Assignee or Owner . . . . . . . . . . .  31
     9.6.  Closing or Obsoleting a Registry  . . . . . . . . . . . .  31
   10. Appeals . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
   11. Mailing Lists . . . . . . . . . . . . . . . . . . . . . . . .  32
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  32
   13. Changes Relative to Earlier Editions of BCP 26  . . . . . . .  32
     13.1.  2013: Changes in This Document Relative to RFC 5226  . .  32
     13.2.  2008: Changes in RFC 5226 Relative to RFC 2434 . . . . .  33
   14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  34
     14.1.  Acknowledgments for This Document (2013) . . . . . . . .  34
     14.2.  Acknowledgments from the second edition (2008) . . . . .  35
     14.3.  Acknowledgments from the first edition (1998)  . . . . .  35
   15. References  . . . . . . . . . . . . . . . . . . . . . . . . .  35
     15.1.  Normative References . . . . . . . . . . . . . . . . . .  35
     15.2.  Informative References . . . . . . . . . . . . . . . . .  35
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  38

1.  Introduction

   Many protocols make use of points of extensibility that use constants
   to identify various protocol parameters.  To ensure that the values
   used in these fields do not have conflicting uses, and to promote
   interoperability, their allocation is often coordinated by a central
   authority.  For IETF protocols, that role is filled by the Internet
   Assigned Numbers Authority (IANA) [RFC2860].  IANA services are
   currently provided by the International Corporation for Assigned
   Names and Numbers (ICANN).

   The Protocol field in the IP header [RFC0791] and MIME media types
   [RFC4288] are two examples of such coordinations.

   In this document, we call the range of possible values for such a
   field a "namespace".  The binding or association of a specific value
   with a particular purpose within a namespace is called an assignment
   (or, variously: an assigned number, assigned value, code point,
   protocol constant, or protocol parameter).  The act of assignment is
   called a registration, and it takes place in the context of a




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   registry.  The terms "assignment" and "registration" are used
   interchangably throughout this document.

   To make assignments in a given namespace prudently, IANA needs
   guidance describing the conditions under which new values should be
   assigned, as well as when and how modifications to existing values
   can be made.  This document defines a framework for the documentation
   of these guidelines by specification authors, in order to assure that
   the guidance given to IANA is clear and addresses the various issues
   that are likely in the operation of a registry.

   Typically, this information is recorded in a dedicated section of the
   specification with the title "IANA Considerations".

1.1.  Keep IANA Considerations for IANA

   The purpose of having a dedicated IANA Considerations section is to
   provide a single place to collect clear and concise information and
   instructions for IANA.  Technical documentation should reside in
   other parts of the document, and should be included by reference
   only.  Using the IANA Considerations section as primary technical
   documentation both hides it from the target audience of the document
   and interferes with IANA's review of the actions they need to take.

   If, for example, the registration of an item in a registry includes a
   short description of the item being registered, that should be placed
   in the IANA Considerations directly.  But if it's necessary to
   include a longer technical explanation of the purpose and use of the
   item, the IANA Considerations should refer to a technical section of
   the document where that information resides.

   An ideal IANA Considerations section clearly enumerates and specifies
   each requested IANA action; includes all information IANA needs, such
   as the full names of all applicable registries; and includes clear
   references to elsewhere in the document for other information.

1.2.  For More Information

   IANA maintains a web page that includes current important information
   from IANA.  Document authors should check that page for additional
   information, beyond what is provided here.

      <http://www.iana.org/important-information>.

   [[CREF1: ***** The URI above is not yet ready.  Make sure IANA sets
   it up. *****]]





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1.3.  Terminology Used In This Document

   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 RFC 2119 [RFC2119].
   For this document, "the specification" as used by RFC 2119 refers to
   the processing of protocol documents within the IETF standards
   process.

2.  Creating and Revising Registries

   Defining a registry involves describing the namespace(s) to be
   created, listing an initial set of assignments (if appropriate), and
   documenting guidelines on how future assignments are to be made.

   Before defining a registry, however, consider delegating the
   namespace in some manner.  This route should be pursued when
   appropriate, as it lessens the burden on IANA for dealing with
   assignments.

   In particular, not all namespaces require a registry; in some cases,
   assignments can be made independently and with no further (central)
   coordination.  In the Domain Name System, for example, IANA only
   deals with assignments at the higher levels, while subdomains are
   administered by the organization to which the space has been
   delegated.  When a namespace is delegated in this manner, the scope
   of IANA is limited to the parts of the namespace where IANA has
   authority.

2.1.  Hierarchical Registry Structure

   It's important to start with a word on the IANA registry structure.
   All registries are anchored from the IANA "Protocol Registries" page:

      <http://www.iana.org/protocols>.
















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   That page lists registries in groups, like this:

     ---------------------------------------------------------------
     Author Domain Signing Practices (ADSP) Parameters

       ADSP Outbound Signing Practices     RFC 5617
                                           IETF Review

       ADSP Specification Tags             RFC 5617
                                           IETF Review

     Automatic Responses to Electronic Mail Parameters

       Auto-Submitted Header Field         RFC 5436
       Keywords                            Specification Required

       Auto-Submitted header field         RFC 3834
       optional parameters                 IETF Consensus

     Autonomous System (AS) Numbers

       16-bit Autonomous System Numbers    RFC 1930, RFC 5398, RFC 6996
                                           RIR request to the IANA
                                           or IETF Review

       32-bit Autonomous System Numbers    RFC 1930, RFC 5398, RFC 6793,
                                           RFC 6996
                                           RIR request to the IANA
                                           or IETF Review
     ---------------------------------------------------------------

   The grouping allows related registries to be placed together, making
   it easier for users of the registries to find the necessary
   information.  In the example section above, there are two registries
   related to the ADSP protocol, and they are both placed in the "ADSP
   Parameters" group.

   Within the "ADSP Parameters" group are two registries: "ADSP Outbound
   Signing Practices" and "ADSP Specification Tags".  Clicking on the
   title of one of these registries on the IANA Protocol Registries page
   will take the reader to the details page for that registry.  Often,
   multiple registries are shown on the same details page.

   Unfortunately, we have been inconsistent in how we refer to these
   entities.  The group names, as they are referred to here, have been
   variously called "groups", "top-level registries", or just
   "registries".  The registries under them have been called
   "registries" or "sub-registries".  And when new registries are



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   created, the documents that define them often don't specify the
   grouping at all, but only name the new registry.  This results in
   questions from IANA and delays in processing, or, worse, in related
   registries that should have been grouped together, but that are
   instead scattered about and hard to find and correlate.

   Regardless of the terminology used, document authors should pay
   attention to the registry groupings, should request that related
   registries be grouped together, and, when creating a new registry,
   should check whether that registry might best be included in an
   existing group.  That grouping information should be clearly
   communicated to IANA in the registry creation request.

2.2.  Documentation Requirements for Registries

   Documents that create a new namespace (or modify the definition of an
   existing space) and that expect IANA to play a role in maintaining
   that space (serving as a repository for registered values) MUST
   provide clear instructions on details of the namespace, either in the
   IANA Considerations section, or referenced from it.

   In particular, such instructions MUST include:

   The name of the registry (or sub-registry)
      This name will appear on the IANA web page and will be referred to
      in future documents that need to allocate a value from the new
      space.  The full name (and abbreviation, if appropriate) should be
      provided.  It is highly desirable that the chosen name not be
      easily confused with the name of another registry.

      When creating a sub-registry, the registry that it is a part of
      must be identified using its full name, exactly as it appears in
      the IANA registry list.

      Providing a URL to precisely identify the registry helps IANA
      understand the request.  Such URLs can be removed from the RFC
      prior to final publication.  If they are to be left in, it is
      important that they be permanent links -- IANA intends to include
      the permalink for each registry in the registry header.

      For example, a document could contain something like this:

         This registration should be made in the Foobar Operational
         Parameters registry, located at <http://www.iana.org/
         assignments/foobar-registry>.






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      It might be tempting to use the URL that appears in your web
      browser's address bar, which might look something like this for
      the example above:

         http://www.iana.org/assignments/foobar-registry/foobar-
         registry.xml

      ...but that is not the permanent link to the registry.

   Required information for registrations

      This information may include the need to document relevant
      Security Considerations, if any.

   Applicable review process

      The review process that will apply to all future requests for
      registration.  See Section 2.3.

   Size, format and syntax of registry entries

      What fields to record in the registry., and any technical
      requirements upon registry entries (e.g., valid ranges for
      integers, length limitations on strings, etc.) as well as the
      exact format in which registry values should be displayed.  For
      numeric assignments, one should specify whether values are to be
      recorded in decimal, hexadecimal, or some other format.  For
      strings, the encoding format should be specified (ASCII, UTF8,
      etc.).

   Initial assignments and reservations

      Any initial assignments or registrations to be included.  In
      addition, any ranges that are to be reserved for "Private Use",
      "Reserved", "Unassigned", etc. should be indicated.
















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   For example, a document might specify a new registry by including:

       ---------------------------------------------------------------

       X. IANA Considerations

       This document defines a new DHCP option, entitled "FooBar" (see
       Section y), assigned a value of TBD1 from the DHCP Option space
       [to be removed upon publication:
       http://www.iana.org/assignments/bootp-dhcp-parameters]
       [RFC2132] [RFC2939]:
                                      Data
             Tag     Name            Length      Meaning
             ----    ----            ------      -------
             TBD1    FooBar          N           FooBar server

       The FooBar option also defines an 8-bit FooType field, for which
       IANA is to create and maintain a new sub-registry entitled
       "FooType values" under the FooBar option.  Initial values for the
       DHCP FooBar FooType registry are given below; future assignments
       are to be made through Expert Review [BCP26].
       Assignments consist of a DHCP FooBar FooType name and its
       associated value.

             Value    DHCP FooBar FooType Name        Definition
             ----     ------------------------        ----------
             0        Reserved
             1        Frobnitz                        See Section y.1
             2        NitzFrob                        See Section y.2
             3-254    Unassigned
             255      Reserved
       ---------------------------------------------------------------

   For examples of documents that establish registries, consult
   [RFC6195], [RFC3575], [RFC3968], and [RFC4520].

2.3.  Defining an Appropriate Registry Policy

   There are several issues to consider when defining the policy for the
   new assignments in a registry.

   If the registry's namespace is limited, assignments will need to be
   made carefully to prevent exhaustion.

   Even when the space is essentially unlimited, however, it is usually
   desirable to have at least a minimal review prior to assignment in
   order to:




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   o  prevent the hoarding of or unnecessary wasting of values.  For
      example, if the space consists of text strings, it may be
      desirable to prevent entities from obtaining large sets of strings
      that correspond to desirable names (existing company names, for
      example).

   o  provide a sanity check that the request actually makes sense and
      is necessary.  Experience has shown that some level of minimal
      review from a subject matter expert is useful to prevent
      assignments in cases where the request is malformed or not
      actually needed (for example, an existing assignment for an
      essentially equivalent service already exists).

   Perhaps most importantly, unreviewed extensions can impact
   interoperability and security.  See [RFC6709].

   When the namespace is essentially unlimited and there are no
   potential interoperability or security issues, assigned numbers can
   usually be given out to anyone without any subjective review.  In
   such cases, IANA can make assignments directly, provided that IANA is
   given detailed instructions on what types of requests it should
   grant, and it is able to do so without exercising subjective
   judgement.

   When this is not the case, some level of review is required.
   However, it's important to balance adequate review and ease of
   registration.  In many cases, those making registrations will not be
   IETF participants; requests often come from other standards
   organizations, from organizations not directly involved in standards,
   from ad-hoc community work (from an open-source project, for
   example), and so on.  Registration must not be unnecessarily
   difficult, unnecessarily costly (in terms of time and other
   resources), nor unnecessarily subject to denial.

   While it is sometimes necessary to restrict what gets registered
   (e.g., for limited resources such as bits in a byte, or for items for
   which unsupported values can be damaging to protocol operation), in
   many cases having what's in use represented in the registry is more
   important.  Overly strict review criteria and excessive cost (in time
   and effort) discourage people from even attempting to make a
   registration.  If a registry fails to reflect the protocol elements
   actually in use, it can adversely affect deployment of protocols on
   the Internet, and the registry itself is devalued.

   In particular, when a registry policy that requires involvement of
   Working Groups, directorates, or other bodies to be actively involved
   and to support the effort, requests frequently run into concerns that
   "it's not worth doing a Standards-Track RFC for something this



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   trivial," when, in fact, that requirement was created by the Working
   Group in the first place, by placing the bar that high.

   Indeed, publishing any RFC is costly, and a Standards Track RFC is
   especially so, requiring a great deal of community time for review
   and discussion, IETF-wide last call, involvement of the entire IESG
   as well as concentrated time and review from the sponsoring AD,
   review and action by IANA, and RFC-Editor processing.

   Therefore, Working Groups and other document developers should use
   care in selecting appropriate registration policies when their
   documents create registries.  They should select the least strict
   policy that suits a registry's needs, and look for specific
   justification for policies that require significant community
   involvement (Specification Required, in terms of the well-known
   policies).

2.3.1.  Using the Well-Known Registration Policies

   This document defines a number of registration policies in Section 4.
   Because they benefit from both community experience and wide
   understanding, their use is encouraged when appropriate.

   It is also acceptable to cite one of the well-known policies and
   include additional guidelines for what kind of considerations should
   be taken into account by the review process.

   For example, RADIUS [RFC3575] specifies the use of a Designated
   Expert, but includes specific additional criteria the Designated
   Expert should follow.

   The well-known policies from "First Come First Served" to "Standards
   Action" specify a range of policies in increasing order of
   strictness:

   4.   First Come First Served
        No review, minimal documentation.

   5.   Expert Review
        Expert review, sufficient documentation for review.

   6.   Specification Required
        Expert review, significant, stable public documentation.

   7.   RFC Required
        Any RFC publication, IETF or a non-IETF Stream.

   8.   IETF Review



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        RFC publication, IETF Stream only, but need not be Standards
        Track.

   9.   Standards Action
        RFC publication, IETF Stream, Standards Track only.

   Examples of situations that might merit RFC Required, IETF Review, or
   Standards Action include the following:

   o  When a resource is limited, such as bits in a byte (or in two
      bytes, or four), or numbers in a limited range.  In these cases,
      allowing registrations that haven't been carefully reviewed and
      agreed by community consensus could too quickly deplete the
      allowable values.

   o  When thorough community review is necessary to avoid extending or
      modifying the protocol in ways that could be damaging.  One
      example is in defining new command codes, as opposed to options
      that use existing command codes: the former might require a strict
      policy, where a more relaxed policy could be adequate for the
      latter.  Another example is in defining protocol elements that
      change the semantics of existing operations.

   The description in Section 4.10 of "IESG Approval" suggests that the
   IESG "can (and should) reject a request if another path for
   registration is available that is more appropriate and there is no
   compelling reason not to use that path."  The IESG should give
   similar consideration to any registration policy more stringent than
   Specification Required, asking for justification and ensuring that
   more relaxed policies have been considered, and the strict policy is
   the right one.

   Accordingly, document developers need to anticipate this and document
   their considerations for selecting the specified policy (ideally, in
   the document itself; failing that, in the shepherd writeup).
   Likewise, the document shepherd should ensure that the selected
   policies have been justified before sending the document to the IESG.

   When specifications are revised, registration policies should be
   reviewed in light of experience since the policies were set.

   Note that the well-known policies are not exclusive; there are
   situations where a different policy might be more appropriate.








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2.3.2.  Using Multiple Policies in Combination

   In some situations, it is necessary to define multiple registration
   policies.  For example, registrations through the normal IETF process
   might use one policy, while registrations from outside the process
   would have a different policy applied.

   Thus, a particular registry might want to use a policy such as "RFC
   Required" or "IETF Review" sometimes, with a designated expert
   checking a "Specification Required" policy at other times.

   The alternative to using a combination requires either that all
   requests come through RFCs or that requests in RFCs go through review
   by the designated expert, even though they already have IETF review
   and consensus.

   This can be documented in the IANA Considerations section when the
   registry is created:

      IANA is asked to create the registry "Fruit Access Flags" as a
      sub-registry of "Fruit Parameters".  New registrations will be
      permitted through either the IETF Review policy or the
      Specification Required policy [BCP26].

   Such combinations will commonly use one of {Standards Action, IETF
   Review, RFC Required} in combination with one of {Specification
   Required, Expert Review}.

2.3.3.  Specifying Change Control for a Registry

   Registry definitions and registrations within registries often need
   to be changed after they are created.  The process of making such
   changes is complicated when it is unclear who is authorized to make
   the changes.  For registries created by RFCs in the IETF stream,
   change control for the registry lies by default with the IETF, via
   the IESG.  The same is true for value registrations made in IETF-
   stream RFCs.

   But registries can be created and registrations can be made outside
   the IETF stream, it can sometimes be desired to have change control
   outside the IETF and IESG, and clear specification of change control
   policies is always helpful.

   It is advised, therefore, that all registries that are created
   clearly specify a change control policy and a change controller.  It
   is also advised that registries that allow registrations from outside
   the IETF stream include, for each value, the designation of a change
   controller for that value.  If the definition or reference for a



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   registered value ever needs to change, or if a registered value needs
   to be deprecated, it is critical that IANA know who is authorized to
   make the change.

2.4.  Revising Existing Registries

   Updating the registration process for an already existing (previously
   created) namespace (whether created explicitly or implicitly) follows
   a process similar to that used when creating a new namespace.  That
   is, a document is produced that makes reference to the existing
   namespace and then provides detailed guidelines for handling
   assignments in each individual namespace.  Such documents are
   normally processed as Best Current Practices (BCPs) [RFC2026].

   Example documents that updated the guidelines for assignments in pre-
   existing registries include: [RFC6195], [RFC3228], and [RFC3575].

3.  Registering New Values in an Existing Registry

3.1.  Documentation Requirements for Registrations

   Often, documents request an assignment from an already existing
   namespace (one created by a previously published document).

   Such documents should clearly identify the namespace in which each
   value is to be registered.  If the registration goes into a sub-
   registry, the author should clearly describe where the assignment or
   registration should go.  Use the exact namespace name as listed on
   the IANA web page, and cite the RFC where the namespace is defined.

   There is no need to mention what the assignment policy for new
   assignments is, as that should be clear from the references.

   When referring to an existing registry, providing a URL to precisely
   identify the registry is helpful.  See Section 2.2 for details on
   specifying the correct URL.

   For example, a document could contain something like this:

      This registration should be made in the Foobar Operational
      Parameters registry, located at <http://www.iana.org/assignments/
      foobar-registry>.

   Each value requested should be given a unique reference.  When the
   value is numeric, use the notation: TBD1, TBD2, etc.  Throughout the
   document where an actual IANA-assigned value should be filled in, use
   the "TBDx" notation.  This helps ensure that the final RFC has the
   correct assigned values inserted in all of the relevant places where



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   the value is expected to appear in the final document.  For values
   that are text strings, a specific name can be suggested.  IANA will
   normally assign the name, unless it conflicts with a name already in
   use.

   Normally, the values to be used are chosen by IANA and documents
   should specify values of "TBD".  However, in some cases, a value may
   have been used for testing or in early implementations.  In such
   cases, it is acceptable to include text suggesting what specific
   value should be used (together with the reason for the choice).  For
   example, one might include the text "the value XXX is suggested as it
   is used in implementations".  However, it should be noted that
   suggested values are just that; IANA will attempt to assign them, but
   may find that impossible, if the proposed number has already been
   assigned for some other use.

   For some registries, IANA has a long-standing policy prohibiting
   assignment of names or codes on a vanity or organization-name basis.
   For example, codes are always assigned sequentially unless there is a
   strong reason for making an exception.  Nothing in this document is
   intended to change those policies or prevent their future
   application.

   The IANA Considerations section should summarize all of the IANA
   actions, with pointers to the relevant sections elsewhere in the
   document as appropriate.  When multiple values are requested, it is
   generally helpful to include a summary table.  It is also helpful for
   this table to be in the same format as it appears or will appear on
   the IANA web site.  For example:


     Value     Description          Reference
     --------  -------------------  ---------
     TBD1      Foobar               [[this RFC]]

   Note: In cases where authors feel that including the full table is
   too verbose or repetitive, authors should still include the table in
   the draft, but may include a note asking that the table be removed
   prior to publication of the final RFC.

   As an example, the following text could be used to request assignment
   of a DHCPv6 option number:

      IANA has assigned an option code value of TBD1 to the DNS
      Recursive Name Server option and an option code value of TBD2 to
      the Domain Search List option from the DHCP option code space
      defined in Section 24.3 of RFC 3315.




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3.2.  Updating Existing Registrations

   Even after a number has been assigned, some types of registrations
   contain additional information that may need to be updated over time.

   For example, MIME media types, character sets, and language tags
   typically include more information than just the registered value
   itself, and may need things such as point-of-contact information,
   security issues, pointers to updates, or literature references
   updated.

   In such cases, the document defining the namespace must clearly state
   who is responsible for maintaining and updating a registration.
   Depending on the registry, it may be appropriate to specify one or
   more of:

   o  Letting registrants and/or nominated change controllers update
      their own registrations, subject to the same constraints and
      review as with new registrations.

   o  Allowing attachment of comments to the registration.  This can be
      useful in cases where others have significant objections to a
      registration, but the author does not agree to change the
      registration.

   o  Designating the IESG, a designated expert, or another entity as
      having the right to change the registrant associated with a
      registration and any requirements or conditions on doing so.  This
      is mainly to get around the problem when a registrant cannot be
      reached in order to make necessary updates.

3.3.  Overriding Registration Procedures

   Experience has shown that the documented IANA considerations for
   individual protocols do not always adequately cover the reality of
   registry operation, or are not sufficiently clear.  In addition,
   documented IANA considerations are sometimes found to be too
   stringent to allow even working group documents (for which there is
   strong consensus) to perform a registration in advance of actual RFC
   publication.

   In order to allow assignments in such cases, the IESG is granted
   authority to override registration procedures and approve assignments
   on a case-by-case basis.

   The intention here is not to overrule properly documented procedures,
   or to obviate the need for protocols to properly document their IANA
   considerations.  Rather, it is to permit assignments in specific



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   cases where it is obvious that the assignment should just be made,
   but updating the IANA process beforehand is too onerous.

   When the IESG is required to take action as described in this
   section, it is a strong indicator that the applicable registration
   procedures should be updated, possibly in parallel with the work that
   instigated it.

3.4.  Early Allocations

   IANA normally takes its actions when a document is approved for
   publication.  There are times, though, when early allocation of a
   value is important for the development of a technology: for example,
   when early implementations are created while the document is still
   under development.

   IANA has a mechanism for handling such early allocations in some
   cases.  See [I-D.cotton-rfc4020bis] for details.

4.  Well-Known Registration Policies

   The following are some defined policies, most of which are in use
   today.  These cover a range of typical policies that have been used
   to describe the procedure for assigning new values in a namespace.
   It is not strictly required that documents use these terms; the
   actual requirement is that the instructions to IANA be clear and
   unambiguous.  However, use of these terms is strongly RECOMMENDED,
   because their meanings are widely understood.  The terms are fully
   explained in the following subsections.



      1.   Private Use
      2.   Experimental Use
      3.   Hierarchical Allocation
      4.   First Come First Served
      5.   Expert Review
      6.   Specification Required
      7.   RFC Required
      8.   IETF Review
      9.   Standards Action
      10.  IESG Approval

   It should be noted that it often makes sense to partition a namespace
   into multiple categories, with assignments within each category
   handled differently.  Many protocols now partition namespaces into
   two or more parts, with one range reserved for Private or
   Experimental Use while other ranges are reserved for globally unique



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   assignments assigned following some review process.  Dividing a
   namespace into ranges makes it possible to have different policies in
   place for different ranges and different use cases.

   Similarly, it will often be useful to specify multiple policies in
   parallel, with each policy being used under different circumstances.
   For more discussion of that topic, see Section 2.3.2.

   Examples:

      LDAP [RFC4520]
      TLS ClientCertificateType Identifiers [RFC5246] (as detailed in
      the subsections below)
      Pseudowire Edge to Edge Emulation (PWE3) [RFC4446]

4.1.  Private Use

   For private or local use only, with the type and purpose defined by
   the local site.  No attempt is made to prevent multiple sites from
   using the same value in different (and incompatible) ways.  There is
   no need for IANA to review such assignments (since IANA does not
   record them) and assignments are not generally useful for broad
   interoperability.  It is the responsibility of the sites making use
   of the Private Use range to ensure that no conflicts occur (within
   the intended scope of use).

   Examples:

      Site-specific options in DHCP [RFC2939]
      Fibre Channel Port Type Registry [RFC4044]
      TLS ClientCertificateType Identifiers 224-255 [RFC5246]

4.2.  Experimental Use

   Experimental Use is similar to Private Use only, but with the purpose
   being to facilitate experimentation.  See [RFC3692] for details.

   Example:

      Experimental Values in IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP
      Headers [RFC4727]

4.3.  Hierarchical Allocation

   With Hierarchical Allocation, delegated administrators are given
   control over part of the namespace, and can assign values in that
   part of the namespace.  IANA makes allocations in the higher levels
   of the namespace according to one of the other policies.



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   Examples:

      DNS names
      Object Identifiers
      IP addresses

4.4.  First Come First Served

   For the First Come First Served policy, assignments are made to
   anyone on a first come, first served basis.  There is no substantive
   review of the request, other than to ensure that it is well-formed
   and doesn't duplicate an existing assignment.  However, requests must
   include a minimal amount of clerical information, such as a point of
   contact (including an email address, and sometimes a postal address)
   and a brief description of how the value will be used.  Additional
   information specific to the type of value requested may also need to
   be provided, as defined by the namespace.  For numbers, the exact
   value is generally assigned by IANA; with names, specific text
   strings can usually be requested.

   Examples:

      SASL mechanism names [RFC4422]
      LDAP Protocol Mechanisms and LDAP Syntax [RFC4520]

4.5.  Expert Review

   (Also called "Designated Expert" in earlier editions of this
   document.)  For the Expert Review policy, review and approval by a
   designated expert (see Section 5) is required.  The required
   documentation and review criteria for use by the designated expert
   should be provided when defining the registry.  For example, see
   Sections 6 and 7.2 in [RFC3748].

   It is particularly important, when using a designated expert, to give
   clear guidance to the expert, laying out criteria for performing an
   evaluation and reasons for rejecting a request.  When specifying a
   policy that involves a designated expert, the IANA Considerations
   SHOULD contain such guidance.  It is also a good idea to include,
   when possible, a sense of whether many registrations are expected
   over time, or if the registry is expected to be updated infrequently
   or in exceptional circumstances only.

   Examples:

      EAP Method Types [RFC3748]
      HTTP Digest AKA algorithm versions [RFC4169]
      URI schemes [RFC4395]



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      GEOPRIV Location Types [RFC4589]

4.6.  Specification Required

   For the Specification Required policy, review and approval by a
   designated expert (see Section 5) is required, and the values and
   their meanings must be documented in a permanent and readily
   available public specification, in sufficient detail so that
   interoperability between independent implementations is possible.
   The designated expert will review the public specification and
   evaluate whether it is sufficiently clear to allow interoperable
   implementations.  The intention behind "permanent and readily
   available" is that a document can reasonably be expected to be
   findable and retrievable long after IANA assignment of the requested
   value.  Publication of an RFC is an ideal means of achieving this
   requirement, but Specification Required is intended to also cover the
   case of a document published outside of the RFC path.  For RFC
   publication, the normal RFC review process is expected to provide the
   necessary review for interoperability, though the designated expert
   may be a particularly well-qualified person to perform such a review.

   When specifying this policy, just use the term "Specification
   Required".  Some specifications have chosen to refer to it as "Expert
   Review with Specification Required", and that only causes confusion.

   Examples:

      Diffserv-aware TE Bandwidth Constraints Model Identifiers
      [RFC4124]
      TLS ClientCertificateType Identifiers 64-223 [RFC5246]
      ROHC Profile Identifiers [RFC5795]

4.7.  RFC Required

   With the RFC Required policy, the registration request, along with
   associated documentation, must be published in an RFC.  The RFC need
   not be in the IETF stream, but may be in any RFC stream (currently an
   RFC may be in the IETF, IRTF, or IAB stream, or an RFC Editor
   Independent Submission [RFC5742]).  Unless otherwise specified, any
   type of RFC is sufficient (currently Standards Track, BCP,
   Informational, Experimental, or Historic).

4.8.  IETF Review

   (Formerly called "IETF Consensus" in the first edition of this
   document.)  With the IETF Review policy, new values are assigned only
   through RFCs in the IETF Stream -- those that have been shepherded




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   through the IESG as AD-Sponsored or IETF working group Documents
   [RFC2026] [RFC5378].

   The intent is that the document and proposed assignment will be
   reviewed by the IETF community (including appropriate IETF working
   groups, directorates, and other experts) and by the IESG, to ensure
   that the proposed assignment will not negatively affect
   interoperability or otherwise extend IETF protocols in an
   inappropriate or damaging manner.  To ensure adequate community
   review, such documents will always undergo an IETF Last Call.

   Examples:

      IPSECKEY Algorithm Types [RFC4025]
      Accounting-Auth-Method AVP values in DIAMETER [RFC4005]
      TLS Extension Types [RFC5246]

4.9.  Standards Action

   For the Standards Action policy, values are assigned only through
   Standards Track RFCs approved by the IESG.

   Examples:

      BGP message types [RFC4271]
      Mobile Node Identifier option types [RFC4283]
      TLS ClientCertificateType Identifiers 0-63 [RFC5246]
      DCCP Packet Types [RFC4340]

4.10.  IESG Approval

   New assignments may be approved by the IESG.  Although there is no
   requirement that the request be documented in an RFC, the IESG has
   discretion to request documents or other supporting materials on a
   case-by-case basis.

   IESG Approval is not intended to be used often or as a "common case";
   indeed, it has seldom been used in practice during the period RFC
   2434 was in effect.  Rather, it is intended to be available in
   conjunction with other policies as a fall-back mechanism in the case
   where one of the other allowable approval mechanisms cannot be
   employed in a timely fashion or for some other compelling reason.
   IESG Approval is not intended to circumvent the public review
   processes implied by other policies that could have been employed for
   a particular assignment.  IESG Approval would be appropriate,
   however, in cases where expediency is desired and there is strong
   consensus (such as from a working group) for making the assignment.




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   The following guidelines are suggested for any evaluation under IESG
   Approval:

   o  The IESG can (and should) reject a request if another path for
      registration is available that is more appropriate and there is no
      compelling reason not to use that path.

   o  Before approving a request, the community should be consulted, via
      a "call for comments" that provides as much information as is
      reasonably possible about the request.

   Examples:

      IPv4 Multicast address assignments [RFC5771]
      IPv4 IGMP Type and Code values [RFC3228]
      Mobile IPv6 Mobility Header Type and Option values [RFC6275]

5.  Designated Experts

5.1.  The Motivation for Designated Experts

   IANA does not define registry policy itself; rather, it carries out
   policies that have been defined by others and published in RFCs.  As
   part of that process, review of proposed registrations is often
   appropriate.

   A common way to ensure such review is for a proposed registration to
   be published as an RFC, as this ensures that the specification is
   publicly and permanently available.  It is particularly important if
   any potential interoperability issues might arise.  For example, some
   assignments are not just assignments, but also involve an element of
   protocol specification.  A new option may define fields that need to
   be parsed and acted on, which (if specified poorly) may not fit
   cleanly with the architecture of other options or the base protocols
   on which they are built.

   In some cases, however, the burden of publishing an RFC in order to
   register a protocol element is excessive.

   However, it is generally still useful (and sometimes necessary) to
   discuss proposed registrations within the community, on a mailing
   list.  Such a mailing list provides opportunity for public review
   prior to assignment, and allows for a consultative process when
   registrants want help in understanding what a proper registration
   should contain.

   While discussion on a mailing list can provide valuable technical
   feedback, opinions may vary and discussions may continue for some



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   time without clear resolution.  In addition, IANA cannot participate
   in all of these mailing lists and cannot determine if or when such
   discussions reach consensus.  Therefore, IANA relies on a "designated
   expert" for advice regarding the specific question of whether an
   assignment should be made.  The designated expert is an individual
   who is responsible for carrying out an appropriate evaluation and
   returning a recommendation to IANA.

   It should be noted that a key motivation for having designated
   experts is for the IETF to provide IANA with a subject matter expert
   to whom the evaluation process can be delegated.  IANA forwards
   requests for an assignment to the expert for evaluation, and the
   expert (after performing the evaluation) informs IANA as to whether
   or not to make the assignment or registration.

   It will often be useful to use a designated expert only some of the
   time, as a supplement to other processes.  For more discussion of
   that topic, see Section 2.3.2.

5.2.  The Role of the Designated Expert

   The designated expert is responsible for coordinating the appropriate
   review of an assignment request.  The review may be wide or narrow,
   depending on the situation and the judgment of the designated expert.
   This may involve consultation with a set of technology experts,
   discussion on a public mailing list, consultation with a working
   group (or its mailing list if the working group has disbanded), etc.
   Ideally, the designated expert follows specific review criteria as
   documented with the protocol that creates or uses the namespace.  See
   the IANA Considerations sections of [RFC3748] and [RFC3575] for
   specific examples.

   Designated experts are expected to be able to defend their decisions
   to the IETF community, and the evaluation process is not intended to
   be secretive or bestow unquestioned power on the expert.  Experts are
   expected to apply applicable documented review or vetting procedures,
   or in the absence of documented criteria, follow generally accepted
   norms such as those in Section 5.3.

   Designated experts are appointed by the IESG, normally upon
   recommendation by the relevant Area Director, either at the time a
   document creating or updating a namespace is approved by the IESG or
   subsequently, when the first registration request is received.
   Because experts originally appointed may later become unavailable,
   the IESG will appoint replacements as necessary.

   For some registries, it has proven useful to have multiple designated
   experts.  Sometimes those experts work together in evaluating a



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   request, while in other cases additional experts serve as backups.
   In cases of disagreement among those experts, it is the
   responsibility of those experts to make a single clear recommendation
   to IANA.  It is not appropriate for IANA to resolve disputes among
   experts.  In extreme situations, such as deadlock, the IESG may need
   to step in to resolve the problem.

   In registries where a pool of experts evaluates requests, the pool
   should have a single chair responsible for defining how requests are
   to be assigned to and reviewed by experts.  In some cases, the expert
   pool may consist of a primary and backups, with the backups involved
   only when the primary expert is unavailable.  In other cases, IANA
   might assign requests to individual members in sequential or
   approximate random order.  In the event that IANA finds itself having
   received conflicting advice from its experts, it is the
   responsibility of the pool's chair to resolve the issue and provide
   IANA with clear instructions.

   A designated expert that is conflicted for a particular review (is,
   for example, an authors or significant proponent of a specification
   related to the registration under review), that expert should recuse
   himself.  In the event that all the designated experts are
   conflicted, they should ask the IESG to designate a temporary expert
   for the conflicted review.

   As the designated experts are appointed by the IESG, they may be
   removed by the IESG.

5.3.  Designated Expert Reviews

   In the years since RFC 2434 was published and has been put to use,
   experience has led to the following observations:

   o  A designated expert must respond in a timely fashion, normally
      within a week for simple requests to a few weeks for more complex
      ones.  Unreasonable delays can cause significant problems for
      those needing assignments, such as when products need code points
      to ship.  This is not to say that all reviews can be completed
      under a firm deadline, but they must be started, and the requester
      and IANA should have some transparency into the process if an
      answer cannot be given quickly.

   o  If a designated expert does not respond to IANA's requests within
      a reasonable period of time, either with a response or with a
      reasonable explanation for the delay (some requests may be
      particularly complex), and if this is a recurring event, IANA must
      raise the issue with the IESG.  Because of the problems caused by
      delayed evaluations and assignments, the IESG should take



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      appropriate actions to ensure that the expert understands and
      accepts his or her responsibilities, or appoint a new expert.

   o  The designated expert is not required to personally bear the
      burden of evaluating and deciding all requests, but acts as a
      shepherd for the request, enlisting the help of others as
      appropriate.  In the case that a request is denied, and rejecting
      the request is likely to be controversial, the expert should have
      the support of other subject matter experts.  That is, the expert
      must be able to defend a decision to the community as a whole.

   When a designated expert is used, the documentation should give clear
   guidance to the designated expert, laying out criteria for performing
   an evaluation and reasons for rejecting a request.  In the case where
   there are no specific documented criteria, the presumption should be
   that a code point should be granted unless there is a compelling
   reason to the contrary.  Possible reasons to deny a request include
   these:

   o  Scarcity of code points, where the finite remaining code points
      should be prudently managed, or when a request for a large number
      of code points is made, when a single code point is the norm.

   o  Documentation is not of sufficient clarity to evaluate or ensure
      interoperability.

   o  The code point is needed for a protocol extension, but the
      extension is not consistent with the documented (or generally
      understood) architecture of the base protocol being extended, and
      would be harmful to the protocol if widely deployed.  It is not
      the intent that "inconsistencies" refer to minor differences "of a
      personal preference nature".  Instead, they refer to significant
      differences such as inconsistencies with the underlying security
      model, implying a change to the semantics of an existing message
      type or operation, requiring unwarranted changes in deployed
      systems (compared with alternate ways of achieving a similar
      result), etc.

   o  The extension would cause problems with existing deployed systems.

   o  The extension would conflict with one under active development by
      the IETF, and having both would harm rather than foster
      interoperability.

   When a designated expert is used, documents MUST NOT name the
   designated expert in the document itself; instead, any suggested
   names should be relayed to the appropriate Area Director at the time




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   the document is sent to the IESG for approval.  This is usually done
   in the document shepherd writeup.

   If the request should also be reviewed on a specific public mailing
   list, its address should be specified.

5.4.  Expert Reviews and the Document Lifecycle

   Review by the designated expert is necessarily done at a particular
   point in time, and represents review of a particular version of the
   document.  Deciding when the review should take place is a question
   of good judgment.  And while re-reviews might be done when it's
   acknowledged that the documentation of the registered item has
   changed substantially, making sure that re-review happens requires
   attention and care.

   It is possible, through carelessness, accident, inattentiveness, or
   even willful disregard, that changes might be made after the
   designated expert's review and approval that would, if the document
   were re-reviewed, cause the expert not to approve the registration.
   It is up to the IESG, with the token held by the responsible Area
   Director, to be alert to such situations and to recognize that such
   changes need to be checked.

6.  Well-Known Registration Status Terminology

   The following labels describe the status of an assignment or range of
   assignments:



      Private Use:  Private use only (not assigned), as described in
            Section 4.1.

      Experimental:  Available for general experimental use as described
            in [RFC3692].  IANA does not record specific assignments for
            any particular use.

      Unassigned:  Not currently assigned, and available for assignment
            via documented procedures.  While it's generally clear that
            any values that are not registered are unassigned and
            available for assignment, it is sometimes useful to
            explicitly specify that situation.  Note that this is
            distinctly different from "Reserved".

      Reserved:  Not assigned and not available for assignment.
            Reserved values are held for special uses, such as to extend




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            the namespace when it becomes exhausted.  Note that this is
            distinctly different from "Unassigned".

            Reserved values can be released for assignment by the change
            controller for the registry (this is often the IESG, for
            registries created by RFCs in the IETF stream).

7.  Documentation References in IANA Registries

   Usually, registries and registry entries include references to
   documentation (RFCs or other documents).  The purpose of these
   references is to provide pointers for implementors to find details
   necessary for implementation, NOT to simply note what document
   created the registry or entry.  Therefore:

   o  If a document registers an item that is defined and explained
      elsewhere, the registered reference should be to that document,
      and not to the document that is merely performing the
      registration.

   o  If the registered item is defined and explained in the current
      document, it is important to include sufficient information to
      enable implementors to understand the item and to create a proper
      implementation.

   o  If the registered item is explained primarily in a specific
      section of the reference document, it is useful to include a
      section reference.  For example, "[RFC9876], Section 3.2", rather
      than just "[RFC9876]".

   o  For documentation of a new registry, the reference should provide
      information about the registry itself, not just a pointer to the
      creation of it.  Useful information includes the purpose of the
      registry, a rationale for its creation, documentation of the
      process and policy for new registrations, guidelines for new
      registrants or designated experts, and other such related
      information.  But note that, while it's important to include this
      information in the document, it needn't (and shouldn't) all be in
      the IANA Considerations section.  See Section 1.1.

8.  What to Do in "bis" Documents

   On occaison, an RFC is issued that obsoletes a previous edition of
   the same document.  We sometimes call these "bis" documents, such as
   when RFC 9876 is updated by draft-ietf-foo-rfc9876bis.  When the
   original document created registries and/or registered entries, there
   is a question of how to handle the IANA Considerations section in the
   "bis" document.



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   If the registrations specify the original document as a reference,
   those registrations should be updated to point to the current (not
   obsolete) documentation for those items.  Usually, that will mean
   changing the reference to be the "bis" document.  There will, though,
   be times when a document updates another, and changes the definitive
   reference for some items, but not for others.  Be sure that the
   references are always set to point to the correct, current
   documentation for each item.

   For example, suppose RFC 9876 registered the "BANANA" flag in the
   "Fruit Access Flags" registry, and the documentation for that flag is
   in Section 3.2.

   The current registry might look, in part, like this:

      Name      Description          Reference
      --------  -------------------  ---------
      BANANA    Flag for bananas     [RFC9876], Section 3.2

   If draft-ietf-foo-rfc9876bis obsoletes RFC 9876 and, because of some
   rearrangement, now documents the flag in Section 4.1.2, the IANA
   Considerations of the bis document might contain text such as this:


      IANA is asked to change the registration information for the
      BANANA flag in the "Fruit Access Flags" registry to the following:

      Name      Description          Reference
      --------  -------------------  ---------
      BANANA    Flag for bananas     [[this RFC]], Section 4.2.1

   In many cases, if there are a number of registered references to the
   original RFC and the document organization has not changed the
   registered section numbering much, it may simply be reasonable to do
   this:

      Because this document obsoletes RFC 9876, IANA is asked to change
      all registration information that references [RFC9876] to instead
      reference [[this RFC]].

   If information for registered items has been or is being moved to
   other documents, then, of course, the registration information should
   be changed to point to those other documents.  In no case is it
   reasonable to leave documentation pointers to the obsoleted document
   for any registries or registered items that are still in current use.






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9.  Miscellaneous Issues

9.1.  When There Are No IANA Actions

   Before an Internet-Draft can be published as an RFC, IANA needs to
   know what actions (if any) it needs to perform.  Experience has shown
   that it is not always immediately obvious whether a document has no
   IANA actions, without reviewing the document in some detail.  In
   order to make it clear to IANA that it has no actions to perform (and
   that the author has consciously made such a determination), such
   documents should include an IANA Considerations section that states:

      This document has no IANA actions.

   This statement, or an equivalent, must only be inserted after the
   working group or individual submitter has carefully verified it to be
   true.  Using such wording as a matter of "boilerplate" or without
   careful consideration can lead to incomplete or incorrect IANA
   actions being performed.

   If a specification makes use of values from a namespace in which
   assignments are not made by IANA, it may be useful to note this fact,
   with wording such as this:

      The values of the Foobar parameter are assigned by the Barfoo
      registry on behalf of the Rabfoo Forum.  Therefore, this document
      has no IANA actions.

   In some cases, the absence of IANA-assigned values may be considered
   valuable information for future readers; in other cases, it may be
   considered of no value once the document has been approved, and may
   be removed before archival publication.  This choice should be made
   clear in the draft, for example, by including a sentence such as

      [RFC Editor: please remove this section prior to publication.]

   or

      [RFC Editor: please do not remove this section.]

9.2.  Namespaces Lacking Documented Guidance

   For all existing RFCs that either explicitly or implicitly rely on
   IANA to make assignments without specifying a precise assignment
   policy, IANA (in consultation with the IESG) will continue to decide
   what policy is appropriate.  Changes to existing policies can always
   be initiated through the normal IETF consensus process.




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   All future RFCs that either explicitly or implicitly rely on IANA to
   register or otherwise administer namespace assignments MUST provide
   guidelines for administration of the namespace.

9.3.  After-the-Fact Registrations

   Occasionally, the IETF becomes aware that an unassigned value from a
   namespace is in use on the Internet or that an assigned value is
   being used for a different purpose than it was registered for.  The
   IETF does not condone such misuse; procedures of the type described
   in this document MUST be applied to such cases.  In the absence of
   specifications to the contrary, values may only be reassigned for a
   different purpose with the consent of the original assignee (when
   possible) and with due consideration of the impact of such a
   reassignment.  In cases of likely controversy, consultation with the
   IESG is advised.

9.4.  Reclaiming Assigned Values

   Reclaiming previously assigned values for reuse is tricky, because
   doing so can lead to interoperability problems with deployed systems
   still using the assigned values.  Moreover, it can be extremely
   difficult to determine the extent of deployment of systems making use
   of a particular value.  However, in cases where the namespace is
   running out of unassigned values and additional ones are needed, it
   may be desirable to attempt to reclaim unused values.  When
   reclaiming unused values, the following (at a minimum) should be
   considered:

   o  Attempts should be made to contact the original party to which a
      value is assigned, to determine if the value was ever used, and if
      so, the extent of deployment.  (In some cases, products were never
      shipped or have long ceased being used.  In other cases, it may be
      known that a value was never actually used at all.)

   o  Reassignments should not normally be made without the concurrence
      of the original requester.  Reclamation under such conditions
      should only take place where there is strong evidence that a value
      is not widely used, and the need to reclaim the value outweighs
      the cost of a hostile reclamation.  In any case, IESG Approval is
      needed in this case.

   o  It may be appropriate to write up the proposed action and solicit
      comments from relevant user communities.  In some cases, it may be
      appropriate to write an RFC that goes through a formal IETF
      process (including IETF Last Call) as was done when DHCP reclaimed
      some of its "Private Use" options [RFC3942].




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9.5.  Contact Person vs Assignee or Owner

   Many registries include designation of a technical or administrative
   contact associated with each entry.  Often, this is recorded as
   contact information for an individual.  It is unclear, though, what
   role the individual has with respect to the registration: is this
   item registered on behalf of the individual, the company the
   individual worked for, or perhaps another organization the individual
   was acting for?

   This matters because some time later, when the individual has changed
   jobs or roles, and perhaps can no longer be contacted, someone might
   want to update the registration.  IANA has no way to know what
   company, organization, or individual should be allowed to take the
   registration over.  For registrations rooted in RFCs, the stream
   owner (such as the IESG or the IAB) can make an overriding decision.
   But in other cases, there is no recourse.

   Registries can include, in addition to a "Contact" field, an
   "Assignee" or "Owner" field that can be used to address this
   situation, giving IANA clear guidance as to the actual owner of the
   registration.  Alternatively, organizations can put an organizational
   role into the "Contact" field in order to make their ownership clear.

9.6.  Closing or Obsoleting a Registry

   Sometimes there is a request to "close" a registry to further
   registrations.  When a registry is closed, no further registrations
   will be accepted.  The information in the registry will still be
   valid and registrations already in the registry can still be updated.

   A closed registry can also be marked as "obsolete", as an indication
   that the information in the registry is no longer in current use.

   Specific entries in a registry can be marked as "obsolete" (no longer
   in use) or "deprecated" (use is not recommended).

   Such changes to registries and registered values are subject to
   normal change controls (see Section 2.3.3).  Any closure,
   obsolescence, or deprecation serves to annotate the registry
   involved; the information in the registry remains there for
   informational and historic purposes.

10.  Appeals

   Appeals of protocol parameter registration decisions can be made
   using the normal IETF appeals process as described in [RFC2026],




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   Section 6.5.  That is, an initial appeal should be directed to the
   IESG, followed (if necessary) by an appeal to the IAB.

11.  Mailing Lists

   All IETF mailing lists associated with evaluating or discussing
   assignment requests as described in this document are subject to
   whatever rules of conduct and methods of list management are
   currently defined by Best Current Practices or by IESG decision.

12.  Security Considerations

   Information that creates or updates a registration needs to be
   authenticated and authorized.  IANA updates registries according to
   instructions in published RFCs and from the IESG.  It also may accept
   clarifications from document authors, relevant working group chairs,
   Designated Experts, and mail list participants, too.

   Information concerning possible security vulnerabilities of a
   protocol may change over time.  Likewise, security vulnerabilities
   related to how an assigned number is used may change as well.  As new
   vulnerabilities are discovered, information about such
   vulnerabilities may need to be attached to existing registrations, so
   that users are not misled as to the true security issues surrounding
   the use of a registered number.

   An analysis of security issues is generally required for all
   protocols that make use of parameters (data types, operation codes,
   keywords, etc.) used in IETF protocols or registered by IANA.  Such
   security considerations are usually included in the protocol document
   [RFC3552].  It is the responsibility of the IANA considerations
   associated with a particular registry to specify what (if any)
   security considerations must be provided when assigning new values,
   and the process for reviewing such claims.

13.  Changes Relative to Earlier Editions of BCP 26

13.1.  2013: Changes in This Document Relative to RFC 5226

   Significant additions:

   o  Added Section 1.1, Keep IANA Considerations for IANA

   o  Added Section 1.2, For More Information

   o  Added Section 2.1, Hierarchical Registry Structure





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   o  Added Section 2.3, Best Practice for Selecting an Appropriate
      Policy.

   o  Added Section 2.3.2, Using Multiple Policies in Combination.

   o  Added Section 2.3.3, Specifying Change Control for a Registry

   o  Added Section 3.4, Early Allocations

   o  Moved well-known policies into a separate section for each,
      subsections of Section 4.

   o  Added Section 5.4, Expert Reviews and the Document Lifecycle

   o  Added Section 7, Documentation References in IANA Registries

   o  Added Section 8, What to Do in "bis" Documents

   o  Added Section 9.5, Contact Person vs Assignee or Owner

   o  Added Section 9.6, Closing or Obsoleting a Registry

   Clarifications and such:

   o  Some reorganization -- moved text around for clarity and easier
      reading.

   o  Made clarifications about identification of IANA registries and
      use of URLs for them.

   o  Clarified the distinction between "Unassigned" and "Reserved".

   o  Made some clarifications in "Expert Review" about instructions to
      the designated expert.

   o  Made some clarifications in "Specification Required" about how to
      declare this policy.

   o  Assorted minor clarifications and editorial changes throughout.

13.2.  2008: Changes in RFC 5226 Relative to RFC 2434

   Changes include:

   o  Major reordering of text to expand descriptions and to better
      group topics such as "updating registries" vs. "creating new
      registries", in order to make it easier for authors to find the
      text most applicable to their needs.



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   o  Numerous editorial changes to improve readability.

   o  Changed the term "IETF Consensus" to "IETF Review" and added more
      clarifications.  History has shown that people see the words "IETF
      Consensus" (without consulting the actual definition) and are
      quick to make incorrect assumptions about what the term means in
      the context of IANA Considerations.

   o  Added "RFC Required" to list of defined policies.

   o  Much more explicit directions and examples of "what to put in
      RFCs".

   o  "Specification Required" now implies use of a Designated Expert to
      evaluate specs for sufficient clarity.

   o  Significantly changed the wording in the Designated Experts
      section.  Main purpose is to make clear that Expert Reviewers are
      accountable to the community, and to provide some guidance for
      review criteria in the default case.

   o  Changed wording to remove any special appeals path.  The normal
      RFC 2026 appeals path is used.

   o  Added a section about reclaiming unused value.

   o  Added a section on after-the-fact registrations.

   o  Added a section indicating that mailing lists used to evaluate
      possible assignments (such as by a Designated Expert) are subject
      to normal IETF rules.

14.  Acknowledgments

14.1.  Acknowledgments for This Document (2013)

   Thomas Narten and Harald Tveit Alvestrand edited the two earlier
   editions of this document (RFCs 2434 and 5226), and Thomas continues
   his role in this third edition.  Much of the text from RFC 5226
   remains in this edition.

   This document has benefited from thorough review and comments by John
   Klensin and Mark Nottingham.

   Special thanks to Mark Nottingham for reorganizing some of the text
   for better organization and readability.





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14.2.  Acknowledgments from the second edition (2008)

   The original acknowledgments section in RFC 5226 was:

   This document has benefited from specific feedback from Jari Arkko,
   Marcelo Bagnulo Braun, Brian Carpenter, Michelle Cotton, Spencer
   Dawkins, Barbara Denny, Miguel Garcia, Paul Hoffman, Russ Housley,
   John Klensin, Allison Mankin, Blake Ramsdell, Mark Townsley, Magnus
   Westerlund, and Bert Wijnen.

14.3.  Acknowledgments from the first edition (1998)

   The original acknowledgments section in RFC 2434 was:

   Jon Postel and Joyce Reynolds provided a detailed explanation on what
   IANA needs in order to manage assignments efficiently, and patiently
   provided comments on multiple versions of this document.  Brian
   Carpenter provided helpful comments on earlier versions of the
   document.  One paragraph in the Security Considerations section was
   borrowed from [RFC4288].

15.  References

15.1.  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.

15.2.  Informative References

   [I-D.cotton-rfc4020bis]
              Cotton, M., "Early IANA Allocation of Standards Track Code
              Points", draft-cotton-rfc4020bis-02 (work in progress),
              October 2013.

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791, September
              1981.

   [RFC2860]  Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
              Understanding Concerning the Technical Work of the
              Internet Assigned Numbers Authority", RFC 2860, June 2000.

   [RFC2939]  Droms, R., "Procedures and IANA Guidelines for Definition
              of New DHCP Options and Message Types", BCP 43, RFC 2939,
              September 2000.



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   [RFC3228]  Fenner, B., "IANA Considerations for IPv4 Internet Group
              Management Protocol (IGMP)", BCP 57, RFC 3228, February
              2002.

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

   [RFC3575]  Aboba, B., "IANA Considerations for RADIUS (Remote
              Authentication Dial In User Service)", RFC 3575, July
              2003.

   [RFC3692]  Narten, T., "Assigning Experimental and Testing Numbers
              Considered Useful", BCP 82, RFC 3692, January 2004.

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, "Extensible Authentication Protocol (EAP)", RFC
              3748, June 2004.

   [RFC3942]  Volz, B., "Reclassifying Dynamic Host Configuration
              Protocol version 4 (DHCPv4) Options", RFC 3942, November
              2004.

   [RFC3968]  Camarillo, G., "The Internet Assigned Number Authority
              (IANA) Header Field Parameter Registry for the Session
              Initiation Protocol (SIP)", BCP 98, RFC 3968, December
              2004.

   [RFC4005]  Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
              "Diameter Network Access Server Application", RFC 4005,
              August 2005.

   [RFC4025]  Richardson, M., "A Method for Storing IPsec Keying
              Material in DNS", RFC 4025, March 2005.

   [RFC4044]  McCloghrie, K., "Fibre Channel Management MIB", RFC 4044,
              May 2005.

   [RFC4124]  Le Faucheur, F., "Protocol Extensions for Support of
              Diffserv-aware MPLS Traffic Engineering", RFC 4124, June
              2005.

   [RFC4169]  Torvinen, V., Arkko, J., and M. Naslund, "Hypertext
              Transfer Protocol (HTTP) Digest Authentication Using
              Authentication and Key Agreement (AKA) Version-2", RFC
              4169, November 2005.





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   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.

   [RFC4283]  Patel, A., Leung, K., Khalil, M., Akhtar, H., and K.
              Chowdhury, "Mobile Node Identifier Option for Mobile IPv6
              (MIPv6)", RFC 4283, November 2005.

   [RFC4288]  Freed, N. and J. Klensin, "Media Type Specifications and
              Registration Procedures", RFC 4288, December 2005.

   [RFC4340]  Kohler, E., Handley, M., and S. Floyd, "Datagram
              Congestion Control Protocol (DCCP)", RFC 4340, March 2006.

   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", BCP 35, RFC
              4395, February 2006.

   [RFC4422]  Melnikov, A. and K. Zeilenga, "Simple Authentication and
              Security Layer (SASL)", RFC 4422, June 2006.

   [RFC4446]  Martini, L., "IANA Allocations for Pseudowire Edge to Edge
              Emulation (PWE3)", BCP 116, RFC 4446, April 2006.

   [RFC4520]  Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
              Considerations for the Lightweight Directory Access
              Protocol (LDAP)", BCP 64, RFC 4520, June 2006.

   [RFC4589]  Schulzrinne, H. and H. Tschofenig, "Location Types
              Registry", RFC 4589, July 2006.

   [RFC4727]  Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
              ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5378]  Bradner, S. and J. Contreras, "Rights Contributors Provide
              to the IETF Trust", BCP 78, RFC 5378, November 2008.

   [RFC5742]  Alvestrand, H. and R. Housley, "IESG Procedures for
              Handling of Independent and IRTF Stream Submissions", BCP
              92, RFC 5742, December 2009.

   [RFC5771]  Cotton, M., Vegoda, L., and D. Meyer, "IANA Guidelines for
              IPv4 Multicast Address Assignments", BCP 51, RFC 5771,
              March 2010.





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   [RFC5795]  Sandlund, K., Pelletier, G., and L-E. Jonsson, "The RObust
              Header Compression (ROHC) Framework", RFC 5795, March
              2010.

   [RFC6195]  Eastlake, D., "Domain Name System (DNS) IANA
              Considerations", RFC 6195, March 2011.

   [RFC6275]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
              in IPv6", RFC 6275, July 2011.

   [RFC6709]  Carpenter, B., Aboba, B., and S. Cheshire, "Design
              Considerations for Protocol Extensions", RFC 6709,
              September 2012.

Authors' Addresses

   Michelle Cotton
   Internet Corporation for Assigned Names and Numbers
   12025 Waterfront Drive, Suite 300
   Los Angeles, CA  90094-2536
   US

   Phone: +1 310 823 9358
   Email: michelle.cotton@icann.org
   URI:   http://www.icann.org/


   Barry Leiba
   Huawei Technologies

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


   Thomas Narten
   IBM Corporation
   3039 Cornwallis Ave., PO Box 12195 - BRQA/502
   Research Triangle Park, NC  27709-2195
   US

   Phone: +1 919 254 7798
   Email: narten@us.ibm.com








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