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rfc:bcp:bcp26

Internet Engineering Task Force (IETF) M. Cotton Request for Comments: 8126 PTI BCP: 26 B. Leiba Obsoletes: 5226 Huawei Technologies Category: Best Current Practice T. Narten ISSN: 2070-1721 IBM Corporation

                                                             June 2017
   Guidelines for Writing an IANA Considerations Section in RFCs

Abstract

 Many protocols make use of points of extensibility that use constants
 to identify various protocol parameters.  To ensure that the values
 in these fields do not have conflicting uses and to promote
 interoperability, their allocations are often coordinated by a
 central record keeper.  For IETF protocols, that role is filled by
 the Internet Assigned Numbers Authority (IANA).
 To make assignments in a given registry prudently, guidance
 describing the conditions under which new values should be assigned,
 as well as when and how modifications to existing values can be made,
 is needed.  This document defines a framework for the documentation
 of these guidelines by specification authors, in order to assure that
 the provided guidance for the IANA Considerations is clear and
 addresses the various issues that are likely in the operation of a
 registry.
 This is the third edition of this document; it obsoletes RFC 5226.

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 represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 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/rfc8126.

Cotton, et al. Best Current Practice [Page 1] RFC 8126 IANA Considerations Section in RFCs June 2017

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.

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   1.1.  Keep IANA Considerations for IANA . . . . . . . . . . . .   4
   1.2.  For Updated Information . . . . . . . . . . . . . . . . .   5
   1.3.  A Quick Checklist Upfront . . . . . . . . . . . . . . . .   5
 2.  Creating and Revising Registries  . . . . . . . . . . . . . .   7
   2.1.  Organization of Registries  . . . . . . . . . . . . . . .   8
   2.2.  Documentation Requirements for Registries . . . . . . . .   8
   2.3.  Specifying Change Control for a Registry  . . . . . . . .  11
   2.4.  Revising Existing Registries  . . . . . . . . . . . . . .  11
 3.  Registering New Values in an Existing Registry  . . . . . . .  12
   3.1.  Documentation Requirements for Registrations  . . . . . .  12
   3.2.  Updating Existing Registrations . . . . . . . . . . . . .  14
   3.3.  Overriding Registration Procedures  . . . . . . . . . . .  14
   3.4.  Early Allocations . . . . . . . . . . . . . . . . . . . .  15
 4.  Choosing a Registration Policy and Well-Known Policies  . . .  15
   4.1.  Private Use . . . . . . . . . . . . . . . . . . . . . . .  18
   4.2.  Experimental Use  . . . . . . . . . . . . . . . . . . . .  18
   4.3.  Hierarchical Allocation . . . . . . . . . . . . . . . . .  19
   4.4.  First Come First Served . . . . . . . . . . . . . . . . .  19
   4.5.  Expert Review . . . . . . . . . . . . . . . . . . . . . .  20
   4.6.  Specification Required  . . . . . . . . . . . . . . . . .  21
   4.7.  RFC Required  . . . . . . . . . . . . . . . . . . . . . .  22
   4.8.  IETF Review . . . . . . . . . . . . . . . . . . . . . . .  22
   4.9.  Standards Action  . . . . . . . . . . . . . . . . . . . .  23
   4.10. IESG Approval . . . . . . . . . . . . . . . . . . . . . .  23
   4.11. Using the Well-Known Registration Policies  . . . . . . .  24
   4.12. Using Multiple Policies in Combination  . . . . . . . . .  26
   4.13. Provisional Registrations . . . . . . . . . . . . . . . .  26

Cotton, et al. Best Current Practice [Page 2] RFC 8126 IANA Considerations Section in RFCs June 2017

 5.  Designated Experts  . . . . . . . . . . . . . . . . . . . . .  27
   5.1.  The Motivation for Designated Experts . . . . . . . . . .  27
   5.2.  The Role of the Designated Expert . . . . . . . . . . . .  27
     5.2.1.  Managing Designated Experts in the IETF . . . . . . .  29
   5.3.  Designated Expert Reviews . . . . . . . . . . . . . . . .  29
   5.4.  Expert Reviews and the Document Lifecycle . . . . . . . .  31
 6.  Well-Known Registration Status Terminology  . . . . . . . . .  31
 7.  Documentation References in IANA Registries . . . . . . . . .  32
 8.  What to Do in "bis" Documents . . . . . . . . . . . . . . . .  33
 9.  Miscellaneous Issues  . . . . . . . . . . . . . . . . . . . .  34
   9.1.  When There Are No IANA Actions  . . . . . . . . . . . . .  34
   9.2.  Namespaces Lacking Documented Guidance  . . . . . . . . .  35
   9.3.  After-the-Fact Registrations  . . . . . . . . . . . . . .  35
   9.4.  Reclaiming Assigned Values  . . . . . . . . . . . . . . .  35
   9.5.  Contact Person vs Assignee or Owner . . . . . . . . . . .  36
   9.6.  Closing or Obsoleting a Registry/Registrations  . . . . .  37
 10. Appeals . . . . . . . . . . . . . . . . . . . . . . . . . . .  37
 11. Mailing Lists . . . . . . . . . . . . . . . . . . . . . . . .  37
 12. Security Considerations . . . . . . . . . . . . . . . . . . .  37
 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  38
 14. Changes Relative to Earlier Editions of BCP 26  . . . . . . .  38
   14.1.  2016: Changes in This Document Relative to RFC 5226  . .  38
   14.2.  2008: Changes in RFC 5226 Relative to RFC 2434 . . . . .  39
 15. References  . . . . . . . . . . . . . . . . . . . . . . . . .  40
   15.1.  Normative References . . . . . . . . . . . . . . . . . .  40
   15.2.  Informative References . . . . . . . . . . . . . . . . .  40
 Acknowledgments for This Document (2017)  . . . . . . . . . . . .  46
 Acknowledgments from the Second Edition (2008)  . . . . . . . . .  46
 Acknowledgments from the First Edition (1998) . . . . . . . . . .  46
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  47

Cotton, et al. Best Current Practice [Page 3] RFC 8126 IANA Considerations Section in RFCs June 2017

1. Introduction

 Many protocols make use of points of extensibility that use constants
 to identify various protocol parameters.  To ensure that the values
 in these fields do not have conflicting uses and to promote
 interoperability, their allocations are often coordinated by a
 central record keeper.  The Protocol field in the IP header [RFC791]
 and MIME media types [RFC6838] are two examples of such
 coordinations.
 The IETF selects an IANA Functions Operator (IFO) for protocol
 parameters defined by the IETF.  In the contract between the IETF and
 the current IFO (ICANN), that entity is referred to as the IANA
 PROTOCOL PARAMETER SERVICES Operator, or IPPSO.  For consistency with
 past practice, the IFO or IPPSO is referred to in this document as
 "IANA" [RFC2860].
 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
 registry.  The terms "assignment" and "registration" are used
 interchangeably throughout this document.
 To make assignments in a given namespace prudently, guidance
 describing the conditions under which new values should be assigned,
 as well as when and how modifications to existing values can be made,
 is needed.  This document defines a framework for the documentation
 of these guidelines by specification authors, in order to assure that
 the guidance for the IANA Considerations 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; the IANA Considerations should refer to
 these other sections by reference only (as needed).  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.

Cotton, et al. Best Current Practice [Page 4] RFC 8126 IANA Considerations Section in RFCs June 2017

 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.
 The IANA actions are normally phrased as requests for IANA (such as,
 "IANA is asked to assign the value TBD1 from the Frobozz
 Registry..."); the RFC Editor will change those sentences to reflect
 the actions taken ("IANA has assigned the value 83 from the Frobozz
 Registry...").

1.2. For Updated Information

 IANA maintains a web page that includes additional clarification
 information beyond what is provided here, such as minor updates and
 summary guidance.  Document authors should check that page.  Any
 significant updates to the best current practice will have to feed
 into updates to BCP 26 (this document), which is definitive.
    <https://iana.org/help/protocol-registration>

1.3. A Quick Checklist Upfront

 It's useful to be familiar with this document as a whole.  But when
 you return for quick reference, here are checklists for the most
 common things you'll need to do and references to help with the less
 common ones.
 In general...
 1.  Put all the information that IANA will need to know into the
     "IANA Considerations" section of your document (see Section 1.1).
 2.  Try to keep that section only for information to IANA and to
     designated expert reviewers; put significant technical
     information in the appropriate technical sections of the document
     (see Section 1.1).
 3.  Note that the IESG has the authority to resolve issues with IANA
     registrations.  If you have any questions or problems, you should
     consult your document shepherd and/or working group chair, who
     may ultimately involve an Area Director (see Section 3.3).

Cotton, et al. Best Current Practice [Page 5] RFC 8126 IANA Considerations Section in RFCs June 2017

 If you are creating a new registry...
 1.  Give the registry a descriptive name and provide a brief
     description of its use (see Section 2.2).
 2.  Identify any registry grouping that it should be part of (see
     Section 2.1).
 3.  Clearly specify what information is required in order to register
     new items (see Section 2.2).  Be sure to specify data types,
     lengths, and valid ranges for fields.
 4.  Specify the initial set of items for the registry, if applicable
     (see Section 2.2).
 5.  Make sure the change control policy for the registry is clear to
     IANA, in case changes to the format or policies need to be made
     later (see Sections 2.3 and 9.5).
 6.  Select a registration policy -- or a set of policies -- to use
     for future registrations (see Section 4, and especially note
     Sections 4.11 and 4.12).
 7.  If you're using a policy that requires a designated expert
     (Expert Review or Specification Required), understand Section 5
     and provide review guidance to the designated expert (see
     Section 5.3).
 8.  If any items or ranges in your registry need to be reserved for
     special use or are otherwise unavailable for assignment, see
     Section 6.
 If you are registering into an existing registry...
 1.  Clearly identify the registry by its exact name and optionally by
     its URL (see Section 3.1).
 2.  If the registry has multiple ranges from which assignments can be
     made, make it clear which range is requested (see Section 3.1).
 3.  Avoid using specific values for numeric or bit assignments, and
     let IANA pick a suitable value at registration time (see
     Section 3.1).  This will avoid registration conflicts among
     multiple documents.

Cotton, et al. Best Current Practice [Page 6] RFC 8126 IANA Considerations Section in RFCs June 2017

 4.  For "reference" fields, use the document that provides the best
     and most current documentation for the item being registered.
     Include section numbers to make it easier for readers to locate
     the relevant documentation (see Sections 3.1 and 7).
 5.  Look up (in the registry's reference document) what information
     is required for the registry and accurately provide all the
     necessary information (see Section 3.1).
 6.  Look up (in the registry's reference document) any special rules
     or processes there may be for the registry, such as posting to a
     particular mailing list for comment, and be sure to follow the
     process (see Section 3.1).
 7.  If the registration policy for the registry does not already
     dictate the change control policy, make sure it's clear to IANA
     what the change control policy is for the item, in case changes
     to the registration need to be made later (see Section 9.5).
 If you're writing a "bis" document or otherwise making older
 documents obsolete, see Section 8.
 If you need to make an early registration, such as for supporting
 test implementations during document development, rather than waiting
 for your document to be finished and approved, see [RFC7120].
 If you need to change the format/contents or policies for an existing
 registry, see Section 2.4.
 If you need to update an existing registration, see Section 3.2.
 If you need to close down a registry because it is no longer needed,
 see Section 9.6.

2. Creating and Revising Registries

 Defining a registry involves describing the namespaces to be created,
 listing an initial set of assignments (if applicable), and
 documenting guidelines on how future assignments are to be made.
 When defining a registry, consider structuring the namespace in such
 a way that only top-level assignments need to be made with central
 coordination, and those assignments can delegate lower-level
 assignments so coordination for them can be distributed.  This
 lessens the burden on IANA for dealing with assignments, and is
 particularly useful in situations where distributed coordinators have
 better knowledge of their portion of the namespace and are better
 suited to handling those assignments.

Cotton, et al. Best Current Practice [Page 7] RFC 8126 IANA Considerations Section in RFCs June 2017

2.1. Organization of Registries

 All registries are anchored from the IANA "Protocol Registries" page:
    <https://www.iana.org/protocols>
 That page lists registries in protocol category groups, placing
 related registries together and making it easier for users of the
 registries to find the necessary information.  Clicking on the title
 of one of the registries on the IANA Protocol Registries page will
 take the reader to the details page for that registry.
 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 "protocol category groups", "groups", "top-level
 registries", or just "registries".  The registries under them have
 been called "registries" or "sub-registries".
 Regardless of the terminology used, document authors should pay
 attention to the registry groupings, should request that related
 registries be grouped together to make related registries easier to
 find, 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
    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 registry, the group that it is a part of must be
    identified using its full name, exactly as it appears in the
    Protocol Registries list.

Cotton, et al. Best Current Practice [Page 8] RFC 8126 IANA Considerations Section in RFCs June 2017

    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 or left in the document for reference.
    If you include iana.org URLs, IANA will provide corrections, if
    necessary, during their review.
 Required information for registrations
    This tells registrants what information they have to include in
    their registration requests.  Some registries require only the
    requested value and a reference to a document where use of the
    value is defined.  Other registries require a more detailed
    registration template that describes relevant security
    considerations, internationalization considerations, and other
    such information.
 Applicable registration policy
    The policy that will apply to all future requests for
    registration.  See Section 4.
 Size, format, and syntax of registry entries
    What fields to record in the registry, any technical requirements
    on registry entries (valid ranges for integers, length limitations
    on strings, and such), and the exact format in which registry
    values should be displayed.  For numeric assignments, one should
    specify whether values are to be recorded in decimal, in
    hexadecimal, or in some other format.
    Strings are expected to be ASCII, and it should be clearly
    specified whether case matters, and whether, for example, strings
    should be shown in the registry in uppercase or lowercase.
    Strings that represent protocol parameters will rarely, if ever,
    need to contain non-ASCII characters.  If non-ASCII characters are
    really necessary, instructions should make it very clear that they
    are allowed and that the non-ASCII characters should be
    represented as Unicode characters using the "(U+XXXX)" convention.
    Anyone creating such a registry should think carefully about this
    and consider internationalization advice such as that in
    [RFC7564], Section 10.

Cotton, et al. Best Current Practice [Page 9] RFC 8126 IANA Considerations Section in RFCs June 2017

 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. (see Section 6) should be
    indicated.
 For example, a document might specify a new registry by including:
  1. ————————————————————–
   X. IANA Considerations
   This document defines a new DHCP option, entitled "FooBar" (see
   Section y), and assigns a value of TBD1 from the DHCP Option space
   <https://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 registry entitled
   "FooType values" used by 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                   RFCXXXX, Section y.1
         2        NitzFrob                   RFCXXXX, Section y.2
         3-254    Unassigned
         255      Reserved
   ---------------------------------------------------------------
 For examples of documents that establish registries, consult
 [RFC3575], [RFC3968], and [RFC4520].
 Any time IANA includes names and contact information in the public
 registry, some individuals might prefer that their contact
 information not be made public.  In such cases, arrangements can be
 made with IANA to keep the contact information private.

Cotton, et al. Best Current Practice [Page 10] RFC 8126 IANA Considerations Section in RFCs June 2017

2.3. 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.
 Because registries can be created and registrations can be made
 outside the IETF stream, it can sometimes be desirable 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
 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.  For example, the Media Types registry [RFC6838]
 includes a "Change Controller" in its registration template.  See
 also Section 9.5.

2.4. Revising Existing Registries

 Updating the registration process or making changes to the format of
 an already existing (previously created) registry (whether created
 explicitly or implicitly) follows a process similar to that used when
 creating a new registry.  That is, a document is produced that makes
 reference to the existing namespace and then provides detailed
 guidance for handling assignments in the registry or detailed
 instructions about the changes required.
 If a change requires a new column in the registry, the instructions
 need to be clear about how to populate that column for the existing
 entries.  Other changes may require similar clarity.
 Such documents are normally processed with the same document status
 as the document that created the registry.  Under some circumstances,
 such as with a straightforward change that is clearly needed (such as
 adding a "status" column), or when an earlier error needs to be
 corrected, the IESG may approve an update to a registry without
 requiring a new document.

Cotton, et al. Best Current Practice [Page 11] RFC 8126 IANA Considerations Section in RFCs June 2017

 Example documents that updated the guidelines for assignments in
 pre-existing registries include: [RFC6895], [RFC3228], and [RFC3575].

3. Registering New Values in an Existing Registry

3.1. Documentation Requirements for Registrations

 Often, documents request an assignment in an existing registry (one
 created by a previously published document).
 Such documents should clearly identify the registry into which each
 value is to be registered.  Use the exact registry name as listed on
 the IANA web page, and cite the RFC where the registry is defined.
 When referring to an existing registry, providing a URL to precisely
 identify the registry is helpful (see Section 2.2).
 There is no need to mention what the assignment policy is when making
 new assignments in existing registries, as that should be clear from
 the references.  However, if multiple assignment policies might
 apply, as in registries with different ranges that have different
 policies, it is important to make it clear which range is being
 requested, so that IANA will know which policy applies and can assign
 a value in the correct range.
 Be sure to provide all the information required for a registration,
 and follow any special processes that are set out for the registry.
 Registries sometimes require the completion of a registration
 template for registration or ask registrants to post their request to
 a particular mailing list for discussion prior to registration.  Look
 up the registry's reference document: the required information and
 special processes should be documented there.
 Normally, numeric values to be used are chosen by IANA when the
 document is approved; drafts should not specify final values.
 Instead, placeholders such as "TBD1" and "TBD2" should be used
 consistently throughout the document, giving each item to be
 registered a different placeholder.  The IANA Considerations should
 ask the RFC Editor to replace the placeholder names with the IANA-
 assigned values.  When drafts need to specify numeric values for
 testing or early implementations, they will either request early
 allocation (see Section 3.4) or use values that have already been set
 aside for testing or experimentation (if the registry in question
 allows that without explicit assignment).  It is important that
 drafts not choose their own values, lest IANA assign one of those
 values to another document in the meantime.  A draft can request a
 specific value in the IANA Considerations section, and IANA will

Cotton, et al. Best Current Practice [Page 12] RFC 8126 IANA Considerations Section in RFCs June 2017

 accommodate such requests when possible, but the proposed number
 might have been assigned to some other use by the time the draft is
 approved.
 Normally, text-string values to be used are specified in the
 document, as collisions are less likely with text strings.  IANA will
 consult with the authors if there is, in fact, a collision, and a
 different value has to be used.  When drafts need to specify string
 values for testing or early implementations, they sometimes use the
 expected final value.  But it is often useful to use a draft value
 instead, possibly including the draft version number.  This allows
 the early implementations to be distinguished from those implementing
 the final version.  A document that intends to use "foobar" in the
 final version might use "foobar-testing-draft-05" for the -05 version
 of the draft, for example.
 For some registries, there is a long-standing policy prohibiting
 assignment of names or codes on a vanity or organization-name basis.
 For example, codes might always be 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.
 As an example, the following text could be used to request assignment
 of a DHCPv6 option number:
    IANA is asked to assign 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.
 The IANA Considerations section should summarize all of the IANA
 actions, with pointers to the relevant sections elsewhere in the
 document as appropriate.  Including section numbers is especially
 useful when the reference document is large; the section numbers will
 make it easier for those searching the reference document to find the
 relevant information.
 When multiple values are requested, it is generally helpful to
 include a summary table of the additions/changes.  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, Section 3.2
   TBD2      Gumbo                this RFC, Section 3.3
   TBD3      Banana               this RFC, Section 3.4

Cotton, et al. Best Current Practice [Page 13] RFC 8126 IANA Considerations Section in RFCs June 2017

 Note: In cases where authors feel that including the full table of
 changes 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.

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 updates to items such as point-of-contact
 information, security issues, pointers to updates, and literature
 references.
 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.

Cotton, et al. Best Current Practice [Page 14] RFC 8126 IANA Considerations Section in RFCs June 2017

 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
 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 above, it is a
 strong indicator that the applicable registration procedures should
 be updated, possibly in parallel with the work that instigated it.
 IANA always has the discretion to ask the IESG for advice or
 intervention when they feel it is needed, such as in cases where
 policies or procedures are unclear to them, where they encounter
 issues or questions they are unable to resolve, or where registration
 requests or patterns of requests appear to be unusual or abusive.

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 [RFC7120] for details.  It is usually not necessary to
 explicitly mark a registry as allowing early allocation, because the
 general rules will apply.

4. Choosing a Registration Policy and Well-Known Policies

 A registration policy is the policy that controls how new assignments
 in a registry are accepted.  There are several issues to consider
 when defining the registration policy.
 If the registry's namespace is limited, assignments will need to be
 made carefully to prevent exhaustion.

Cotton, et al. Best Current Practice [Page 15] RFC 8126 IANA Considerations Section in RFCs June 2017

 Even when the space is essentially unlimited, it is still often
 desirable to have at least a minimal review prior to assignment in
 order to:
 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
 judgment.
 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.

Cotton, et al. Best Current Practice [Page 16] RFC 8126 IANA Considerations Section in RFCs June 2017

 Therefore, it is important to think specifically about the
 registration policy, and not just pick one arbitrarily nor copy text
 from another document.  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 (those stricter than Expert Review or Specification
 Required, in terms of the well-known policies).  The needs here will
 vary from registry to registry, and, indeed, over time, and this BCP
 will not be the last word on the subject.
 The following policies are defined for common usage.  These cover a
 range of typical policies that have been used to describe the
 procedures 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.  Newly minted policies,
 including ones that combine the elements of procedures associated
 with these terms in novel ways, may be used if none of these policies
 are suitable; it will help the review process if an explanation is
 included as to why that is the case.  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
 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 4.12.

Cotton, et al. Best Current Practice [Page 17] RFC 8126 IANA Considerations Section in RFCs June 2017

 Examples of RFCs that specify multiple policies in parallel:
    LDAP [RFC4520]
    TLS ClientCertificateType Identifiers [RFC5246] (as detailed in
    the subsections below)
    MPLS Pseudowire Types Registry [RFC4446]

4.1. Private Use

 Private Use is 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.  IANA does not record assignments from registries
 or ranges with this policy (and therefore there is no need for IANA
 to review 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, but with the purpose
 being to facilitate experimentation.  See [RFC3692] for details.
 IANA does not record assignments from registries or ranges with this
 policy (and therefore there is no need for IANA to review them) and
 assignments are not generally useful for broad interoperability.
 Unless the registry explicitly allows it, it is not appropriate for
 documents to select explicit values from registries or ranges with
 this policy.  Specific experiments will select a value to use during
 the experiment.
 When code points are set aside for Experimental Use, it's important
 to make clear any expected restrictions on experimental scope.  For
 example, say whether it's acceptable to run experiments using those
 code points over the open Internet or whether such experiments should
 be confined to more closed environments.  See [RFC6994] for an
 example of such considerations.
 Example:
    Experimental Values in IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP
    Headers [RFC4727]

Cotton, et al. Best Current Practice [Page 18] RFC 8126 IANA Considerations Section in RFCs June 2017

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.
 Examples:
 o  DNS names - IANA manages the top-level domains (TLDs), and, as
    [RFC1591] says:
       Under each TLD may be created a hierarchy of names.  Generally,
       under the generic TLDs the structure is very flat.  That is,
       many organizations are registered directly under the TLD, and
       any further structure is up to the individual organizations.
 o  Object Identifiers - defined by ITU-T recommendation X.208.
    According to <http://www.alvestrand.no/objectid/>, some registries
    include
  • IANA, which hands out OIDs under the "Private Enterprises"

branch,

  • ANSI, which hands out OIDs under the "US Organizations" branch,

and

  • BSI, which hands out OIDs under the "UK Organizations" branch.
 o  URN namespaces - IANA registers URN Namespace IDs (NIDs
    [RFC8141]), and the organization registering an NID is responsible
    for allocations of URNs within that namespace.

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, IANA
 generally assigns the next in-sequence unallocated value, but other
 values may be requested and assigned if an extenuating circumstance
 exists.  With names, specific text strings can usually be requested.

Cotton, et al. Best Current Practice [Page 19] RFC 8126 IANA Considerations Section in RFCs June 2017

 When creating a new registry with First Come First Served as the
 registration policy, in addition to the contact person field or
 reference, the registry should contain a field for change controller.
 Having a change controller for each entry for these types of
 registrations makes authorization of future modifications more clear.
 See Section 2.3.
 It is important that changes to the registration of a First Come
 First Served code point retain compatibility with the current usage
 of that code point, so changes need to be made with care.  The change
 controller should not, in most cases, be requesting incompatible
 changes nor repurposing a registered code point.  See also Sections
 9.4 and 9.5.
 A working group or any other entity that is developing a protocol
 based on a First Come First Served code point has to be extremely
 careful that the protocol retains wire compatibility with current use
 of the code point.  Once that is no longer true, the new work needs
 to change to a different code point (and register that use at the
 appropriate time).
 It is also important to understand that First Come First Served
 really has no filtering.  Essentially, any well-formed request is
 accepted.
 Examples:
    SASL mechanism names [RFC4422]
    LDAP Protocol Mechanisms and LDAP Syntax [RFC4520]

4.5. Expert Review

 For the Expert Review policy, review and approval by a designated
 expert (see Section 5) is required.  While this does not necessarily
 require formal documentation, information needs to be provided with
 the request for the designated expert to evaluate.  The registry's
 definition needs to make clear to registrants what information is
 necessary.  The actual process for requesting registrations is
 administered by IANA (see Section 1.2 for details).
 (This policy was also called "Designated Expert" in earlier editions
 of this document.  The current term is "Expert Review".)
 The required documentation and review criteria, giving clear guidance
 to the designated expert, should be provided when defining the
 registry.  It is particularly important to lay out what should be
 considered when performing an evaluation and reasons for rejecting a
 request.  It is also a good idea to include, when possible, a sense

Cotton, et al. Best Current Practice [Page 20] RFC 8126 IANA Considerations Section in RFCs June 2017

 of whether many registrations are expected over time, or if the
 registry is expected to be updated infrequently or in exceptional
 circumstances only.
 Thorough understanding of Section 5 is important when deciding on an
 Expert Review policy and designing the guidance to the designated
 expert.
 Good examples of guidance to designated experts:
    Extensible Authentication Protocol (EAP) [RFC3748], Sections 6 and
    7.2
    North-Bound Distribution of Link-State and TE Information Using
    BGP [RFC7752], Section 5.1
 When creating a new registry with Expert Review as the registration
 policy, in addition to the contact person field or reference, the
 registry should contain a field for change controller.  Having a
 change controller for each entry for these types of registrations
 makes authorization of future modifications more clear.  See
 Section 2.3.
 Examples:
    EAP Method Types [RFC3748]
    HTTP Digest AKA algorithm versions [RFC4169]
    URI schemes [RFC7595]
    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.
 This policy is the same as Expert Review, with the additional
 requirement of a formal public specification.  In addition to the
 normal review of such a request, the designated expert will review
 the public specification and evaluate whether it is sufficiently
 stable and permanent, and sufficiently clear and technically sound 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

Cotton, et al. Best Current Practice [Page 21] RFC 8126 IANA Considerations Section in RFCs June 2017

 document published outside of the RFC path, including informal
 documentation.
 For RFC publication, formal review by the designated expert is still
 requested, but the normal RFC review process is expected to provide
 the necessary review for interoperability.  The designated expert's
 review is still important, but it's equally important to note that
 when there is IETF consensus, the expert can sometimes be "in the
 rough" (see also the last paragraph of Section 5.4).
 As with Expert Review (Section 4.5), clear guidance to the designated
 expert should be provided when defining the registry, and thorough
 understanding of Section 5 is important.
 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, IAB, or Independent Submission streams
 [RFC5742]).
 Unless otherwise specified, any type of RFC is sufficient (currently
 Standards Track, BCP, Informational, Experimental, or Historic).
 Examples:
    DNSSEC DNS Security Algorithm Numbers [RFC6014]
    Media Control Channel Framework registries [RFC6230]
    DANE TLSA Certificate Usages [RFC6698]

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
 through the IESG as AD-Sponsored or IETF working group documents

Cotton, et al. Best Current Practice [Page 22] RFC 8126 IANA Considerations Section in RFCs June 2017

 [RFC2026] [RFC5378], have gone through IETF Last Call, and have been
 approved by the IESG as having IETF consensus.
 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.
 Unless otherwise specified, any type of RFC is sufficient (currently
 Standards Track, BCP, Informational, Experimental, or Historic).
 Examples:
    IPSECKEY Algorithm Types [RFC4025]
    TLS Extension Types [RFC5246]

4.9. Standards Action

 For the Standards Action policy, values are assigned only through
 Standards Track or Best Current Practice RFCs in the IETF Stream.
 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
 the 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.  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.

Cotton, et al. Best Current Practice [Page 23] RFC 8126 IANA Considerations Section in RFCs June 2017

 Before approving a request, the IESG might consider consulting the
 community, 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]

4.11. Using the Well-Known Registration Policies

 Because the well-known policies benefit from both community
 experience and wide understanding, their use is encouraged, and the
 creation of new policies needs to be accompanied by reasonable
 justification.
 It is also acceptable to cite one or more well-known policies and
 include additional guidelines for what kind of considerations should
 be taken into account by the review process.
 For example, for media-type registrations [RFC6838], a number of
 different situations are covered that involve the use of IETF Review
 and Specification Required, while also including specific additional
 criteria the designated expert should follow.  This is not meant to
 represent a registration procedure, but to show an example of what
 can be done when special circumstances need to be covered.
 The well-known policies from "First Come First Served" to "Standards
 Action" specify a range of policies in increasing order of strictness
 (using the numbering from the full list in Section 4):
 4. First Come First Served
    No review, minimal documentation.
 5 and 6  (of equal strictness).
    5. Expert Review
       Expert review with sufficient documentation for review.
    6. Specification Required
       Significant stable public documentation sufficient for
       interoperability.
 7. RFC Required
    Any RFC publication, IETF or a non-IETF Stream.
 8. IETF Review

Cotton, et al. Best Current Practice [Page 24] RFC 8126 IANA Considerations Section in RFCs June 2017

    RFC publication, IETF Stream only, but need not be Standards
    Track.
 9. Standards Action
    RFC publication, IETF Stream, Standards Track or BCP only.
 Examples of situations that might merit 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 to 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.
 o  When there are security implications with respect to the resource,
    and thorough review is needed to ensure that the new usage is
    sound.  Examples of this include lists of acceptable hashing and
    cryptographic algorithms, and assignment of transport ports in the
    system range.
 When reviewing a document that asks IANA to create a new registry or
 change a registration policy to any policy more stringent than Expert
 Review or Specification Required, the IESG should ask for
 justification to ensure that more relaxed policies have been
 considered and that the more 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.

4.12. Using Multiple Policies in Combination

 In some situations, it is necessary to define multiple registration
 policies.  For example, registrations through the normal IETF process

Cotton, et al. Best Current Practice [Page 25] RFC 8126 IANA Considerations Section in RFCs June 2017

 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, for example:
    IANA is asked to create the registry "Fruit Access Flags" under
    the "Fruit Parameters" group.  New registrations will be permitted
    through either the IETF Review policy or the Specification
    Required policy [BCP26].  The latter should be used only for
    registrations requested by SDOs outside the IETF.  Registrations
    requested in IETF documents will be subject to IETF review.
 Such combinations will commonly use one of {Standards Action, IETF
 Review, RFC Required} in combination with one of {Specification
 Required, Expert Review}.  Guidance should be provided about when
 each policy is appropriate, as in the example above.

4.13. Provisional Registrations

 Some existing registries have policies that allow provisional
 registration: see URI Schemes [RFC7595] and Email Header Fields
 [RFC3864].  Registrations that are designated as provisional are
 usually defined as being more readily created, changed, reassigned,
 moved to another status, or removed entirely.  URI Schemes, for
 example, allow provisional registrations to be made with incomplete
 information.
 Allowing provisional registration ensures that the primary goal of
 maintaining a registry -- avoiding collisions between incompatible
 semantics -- is achieved without the side effect of "endorsing" the
 protocol mechanism the provisional value is used for.  Provisional
 registrations for codepoints that are ultimately standardized can be
 promoted to permanent status.  The criteria that are defined for
 converting a provisional registration to permanent will likely be
 more strict than those that allowed the provisional registration.
 If your registry does not have a practical limit on codepoints,
 perhaps adding the option for provisional registrations might be

Cotton, et al. Best Current Practice [Page 26] RFC 8126 IANA Considerations Section in RFCs June 2017

 right for that registry as well.

5. Designated Experts

5.1. The Motivation for Designated Experts

 Discussion on a mailing list can provide valuable technical feedback,
 but opinions often vary and discussions may continue for some 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.  In most cases, the
 registrants do not work directly with the designated experts.  The
 list of designated experts for a registry is listed in the registry.
 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 4.12.

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 generally

Cotton, et al. Best Current Practice [Page 27] RFC 8126 IANA Considerations Section in RFCs June 2017

 not expected to be "gatekeepers", setting out to make registrations
 difficult to obtain, unless the guidance in the defining document
 specifies that they should act as such.  Absent stronger guidance,
 the experts should be evaluating registration requests for
 completeness, interoperability, and conflicts with existing protocols
 and options.
 It has proven useful to have multiple designated experts for some
 registries.  Sometimes those experts work together in evaluating a
 request, while in other cases additional experts serve as backups,
 acting only when the primary expert is unavailable.  In registries
 with a pool of experts, the pool often has a single chair responsible
 for defining how requests are to be assigned to and reviewed by
 experts.  In other cases, IANA might assign requests to individual
 members in sequential or approximate random order.  The document
 defining the registry can, if it's appropriate for the situation,
 specify how the group should work -- for example, it might be
 appropriate to specify rough consensus on a mailing list, within a
 related working group or among a pool of designated experts.
 In cases of disagreement among multiple 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 designating
 body may need to step in to resolve the problem.
 If a designated expert has a conflict of interest for a particular
 review (is, for example, an author 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 that a temporary expert be designated
 for the conflicted review.  The responsible AD may then appoint
 someone or the AD may handle the review.
 This document defines the designated expert mechanism with respect to
 documents in the IETF stream only.  If other streams want to use
 registration policies that require designated experts, it is up to
 those streams (or those documents) to specify how those designated
 experts are appointed and managed.  What is described below, with
 management by the IESG, is only appropriate for the IETF stream.

5.2.1. Managing Designated Experts in the IETF

 Designated experts for registries created by the IETF are appointed
 by the IESG, normally upon recommendation by the relevant Area
 Director.  They may be appointed 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

Cotton, et al. Best Current Practice [Page 28] RFC 8126 IANA Considerations Section in RFCs June 2017

 originally appointed may later become unavailable, the IESG will
 appoint replacements as necessary.  The IESG may remove any
 designated expert that it appointed, at its discretion.
 The normal appeals process, as described in [RFC2026], Section 6.5.1,
 applies to issues that arise with the designated expert team.  For
 this purpose, the designated expert team takes the place of the
 working group in that description.

5.3. Designated Expert Reviews

 In the years since [RFC2434] was published and 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
    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 (and see also Section 5.4).  Reasons that have
 been used to deny requests have included these:

Cotton, et al. Best Current Practice [Page 29] RFC 8126 IANA Considerations Section in RFCs June 2017

 o  Scarcity of code points, where the finite remaining code points
    should be prudently managed, or where a request for a large number
    of code points is made and 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.
 Documents must not name the designated expert(s) in the document
 itself; instead, any suggested names should be relayed to the
 appropriate Area Director at the time 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.

Cotton, et al. Best Current Practice [Page 30] RFC 8126 IANA Considerations Section in RFCs June 2017

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.  While reviews are generally done around the time of IETF
 Last Call, deciding when the review should take place is a question
 of good judgment.  And while rereviews might be done when it's
 acknowledged that the documentation of the registered item has
 changed substantially, making sure that rereview 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 rereviewed, 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.
 For registrations made from documents on the Standards Track, there
 is often expert review required (by the registration policy) in
 addition to IETF consensus (for approval as a Standards Track RFC).
 In such cases, the review by the designated expert needs to be
 timely, submitted before the IESG evaluates the document.  The IESG
 should generally not hold the document up waiting for a late review.
 It is also not intended for the expert review to override IETF
 consensus: the IESG should consider the review in its own evaluation,
 as it would do for other Last Call reviews.

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".

Cotton, et al. Best Current Practice [Page 31] RFC 8126 IANA Considerations Section in RFCs June 2017

    Reserved:  Not assigned and not available for assignment.
          Reserved values are held for special uses, such as to extend
          the namespace when it becomes exhausted.  "Reserved" is also
          sometimes used to designate values that had been assigned
          but are no longer in use, keeping them set aside as long as
          other unassigned values are available.  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).
    Known Unregistered Use:  It's known that the assignment or range
          is in use without having been defined in accordance with
          reasonable practice.  Documentation for use of the
          assignment or range may be unavailable, inadequate, or
          conflicting.  This is a warning against use, as well as an
          alert to network operators who might see these values in use
          on their networks.

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 the document
    containing the definition, 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, "[RFC4637], Section 3.2", rather
    than just "[RFC4637]".
 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

Cotton, et al. Best Current Practice [Page 32] RFC 8126 IANA Considerations Section in RFCs June 2017

    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 all be in the IANA
    Considerations section.  See Section 1.1.

8. What to Do in "bis" Documents

 On occasion, an RFC is issued that obsoletes a previous edition of
 the same document.  We sometimes call these "bis" documents, such as
 when RFC 4637 is to be obsoleted by draft-ietf-foo-rfc4637bis.  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.
 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, but
 does not make it obsolete, and the definitive reference is changed
 for some items but not for others.  Be sure that the references
 always point to the correct, current documentation for each item.
 For example, suppose RFC 4637 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     [RFC4637], Section 3.2
 If draft-ietf-foo-rfc4637bis obsoletes RFC 4637 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

Cotton, et al. Best Current Practice [Page 33] RFC 8126 IANA Considerations Section in RFCs June 2017

 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 4637, IANA is asked to change
    all registration information that references [RFC4637] to instead
    reference [[this RFC]].
 If information for registered items has been or is being moved to
 other documents, then the registration information should be changed
 to point to those other documents.  In most cases, documentation
 references should not be left pointing to the obsoleted document for
 registries or registered items that are still in current use.  For
 registries or registered items that are no longer in current use, it
 will usually make sense to leave the references pointing to the old
 document -- the last current reference for the obsolete items.  The
 main point is to make sure that the reference pointers are as useful
 and current as is reasonable, and authors should consider that as
 they write the IANA Considerations for the new document.  As always:
 do the right thing, and there is flexibility to allow for that.
 It is extremely important to be clear in your instructions regarding
 updating references, especially in cases where some references need
 to be updated and others do not.

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, after the authors confirm that this is the case,
 include an IANA Considerations section that states:
    This document has no IANA actions.
 IANA prefers that these "empty" IANA Considerations sections be left
 in the document for the record: it makes it clear later on that the
 document explicitly said that no IANA actions were needed (and that
 it wasn't just omitted).  This is a change from the prior practice of
 requesting that such sections be removed by the RFC Editor, and
 authors are asked to accommodate this change.

Cotton, et al. Best Current Practice [Page 34] RFC 8126 IANA Considerations Section in RFCs June 2017

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 will work with the IESG to decide what policy is
 appropriate.  Changes to existing policies can always be initiated
 through the normal IETF consensus process, or through the IESG when
 appropriate.
 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 need to be applied to such cases, and it might not
 always be possible to formally assign the desired value.  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.
 This is part of the reason for the advice in Section 3.1 about using
 placeholder values, such as "TBD1", during document development:
 problems are often caused by the open use of unregistered values
 after results from well-meant, early implementations, where the
 implementations retained the use of developmental code points that
 never proceeded to a final IANA assignment.

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:

Cotton, et al. Best Current Practice [Page 35] RFC 8126 IANA Considerations Section in RFCs June 2017

 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.  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].
 o  It may be useful to differentiate between revocation, release, and
    transfer.  Revocation occurs when IANA removes an assignment,
    release occurs when the assignee initiates that removal, and
    transfer occurs when either revocation or release is coupled with
    immediate reassignment.  It may be useful to specify procedures
    for each of these or to explicitly prohibit combinations that are
    not desired.

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 (also referred to as "Change Controller")
 that can be used to address this situation, giving IANA clear

Cotton, et al. Best Current Practice [Page 36] RFC 8126 IANA Considerations Section in RFCs June 2017

 guidance as to the actual owner of the registration.  This is
 strongly advised, especially for registries that do not require RFCs
 to manage their information (e.g., registries with policies such as
 First Come First Served (Section 4.4), Expert Review (Section 4.5),
 and Specification Required (Section 4.6)).  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/Registrations

 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).  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],
 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 may also accept
 clarifications from document authors, relevant working group chairs,
 designated experts, and mail list participants.

Cotton, et al. Best Current Practice [Page 37] RFC 8126 IANA Considerations Section in RFCs June 2017

 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.
 Security needs to be considered as part of the selection of a
 registration policy.  For some protocols, registration of certain
 parameters will have security implications, and registration policies
 for the relevant registries must ensure that requests get appropriate
 review with those security implications in mind.
 An analysis of security issues is generally required for all
 protocols that make use of parameters (data types, operation codes,
 keywords, etc.) documented in IETF protocols or registered by IANA.
 Such security considerations are usually included in the protocol
 document [BCP72].  It is the responsibility of the IANA
 considerations associated with a particular registry to specify
 whether value-specific security considerations must be provided when
 assigning new values and the process for reviewing such claims.

13. IANA Considerations

 Sitewide, IANA has replaced references to RFC 5226 with references to
 this document.

14. Changes Relative to Earlier Editions of BCP 26

14.1. 2016: Changes in This Document Relative to RFC 5226

 Significant additions:
 o  Removed RFC 2119 key words, boilerplate, and reference, preferring
    plain English -- this is not a protocol specification.
 o  Added Section 1.1, Keep IANA Considerations for IANA
 o  Added Section 1.2, For Updated Information
 o  Added Section 2.1, Organization of Registries
 o  Added best practice for selecting an appropriate policy into
    Section 4.
 o  Added Section 4.12, Using Multiple Policies in Combination

Cotton, et al. Best Current Practice [Page 38] RFC 8126 IANA Considerations Section in RFCs June 2017

 o  Added Section 2.3, Specifying Change Control for a Registry
 o  Added Section 3.4, Early Allocations
 o  Moved each well-known policy into a separate subsection 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/Registrations
 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.

14.2. 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.
 o  Numerous editorial changes to improve readability.

Cotton, et al. Best Current Practice [Page 39] RFC 8126 IANA Considerations Section in RFCs June 2017

 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  Added a section describing provisional registrations.
 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 values.
 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.

15. References

15.1. Normative References

 [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
            3", BCP 9, RFC 2026, DOI 10.17487/RFC2026, October 1996,
            <http://www.rfc-editor.org/info/rfc2026>.

15.2. Informative References

 [BCP72]    Rescorla, E. and B. Korver, "Guidelines for Writing RFC
            Text on Security Considerations", BCP 72, RFC 3552, July
            2003, <http://www.rfc-editor.org/info/bcp72>.

Cotton, et al. Best Current Practice [Page 40] RFC 8126 IANA Considerations Section in RFCs June 2017

 [RFC791]   Postel, J., "Internet Protocol", STD 5, RFC 791,
            DOI 10.17487/RFC0791, September 1981,
            <http://www.rfc-editor.org/info/rfc791>.
 [RFC1591]  Postel, J., "Domain Name System Structure and Delegation",
            RFC 1591, DOI 10.17487/RFC1591, March 1994,
            <http://www.rfc-editor.org/info/rfc1591>.
 [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", RFC 2434,
            DOI 10.17487/RFC2434, October 1998,
            <http://www.rfc-editor.org/info/rfc2434>.
 [RFC2860]  Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
            Understanding Concerning the Technical Work of the
            Internet Assigned Numbers Authority", RFC 2860,
            DOI 10.17487/RFC2860, June 2000,
            <http://www.rfc-editor.org/info/rfc2860>.
 [RFC2939]  Droms, R., "Procedures and IANA Guidelines for Definition
            of New DHCP Options and Message Types", BCP 43, RFC 2939,
            DOI 10.17487/RFC2939, September 2000,
            <http://www.rfc-editor.org/info/rfc2939>.
 [RFC3228]  Fenner, B., "IANA Considerations for IPv4 Internet Group
            Management Protocol (IGMP)", BCP 57, RFC 3228,
            DOI 10.17487/RFC3228, February 2002,
            <http://www.rfc-editor.org/info/rfc3228>.
 [RFC3575]  Aboba, B., "IANA Considerations for RADIUS (Remote
            Authentication Dial In User Service)", RFC 3575,
            DOI 10.17487/RFC3575, July 2003,
            <http://www.rfc-editor.org/info/rfc3575>.
 [RFC3692]  Narten, T., "Assigning Experimental and Testing Numbers
            Considered Useful", BCP 82, RFC 3692,
            DOI 10.17487/RFC3692, January 2004,
            <http://www.rfc-editor.org/info/rfc3692>.
 [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
            Levkowetz, Ed., "Extensible Authentication Protocol
            (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
            <http://www.rfc-editor.org/info/rfc3748>.
 [RFC3864]  Klyne, G., Nottingham, M., and J. Mogul, "Registration
            Procedures for Message Header Fields", BCP 90, RFC 3864,
            DOI 10.17487/RFC3864, September 2004,
            <http://www.rfc-editor.org/info/rfc3864>.

Cotton, et al. Best Current Practice [Page 41] RFC 8126 IANA Considerations Section in RFCs June 2017

 [RFC3942]  Volz, B., "Reclassifying Dynamic Host Configuration
            Protocol version 4 (DHCPv4) Options", RFC 3942,
            DOI 10.17487/RFC3942, November 2004,
            <http://www.rfc-editor.org/info/rfc3942>.
 [RFC3968]  Camarillo, G., "The Internet Assigned Number Authority
            (IANA) Header Field Parameter Registry for the Session
            Initiation Protocol (SIP)", BCP 98, RFC 3968,
            DOI 10.17487/RFC3968, December 2004,
            <http://www.rfc-editor.org/info/rfc3968>.
 [RFC4025]  Richardson, M., "A Method for Storing IPsec Keying
            Material in DNS", RFC 4025, DOI 10.17487/RFC4025, March
            2005, <http://www.rfc-editor.org/info/rfc4025>.
 [RFC4044]  McCloghrie, K., "Fibre Channel Management MIB", RFC 4044,
            DOI 10.17487/RFC4044, May 2005,
            <http://www.rfc-editor.org/info/rfc4044>.
 [RFC4124]  Le Faucheur, F., Ed., "Protocol Extensions for Support of
            Diffserv-aware MPLS Traffic Engineering", RFC 4124,
            DOI 10.17487/RFC4124, June 2005,
            <http://www.rfc-editor.org/info/rfc4124>.
 [RFC4169]  Torvinen, V., Arkko, J., and M. Naslund, "Hypertext
            Transfer Protocol (HTTP) Digest Authentication Using
            Authentication and Key Agreement (AKA) Version-2",
            RFC 4169, DOI 10.17487/RFC4169, November 2005,
            <http://www.rfc-editor.org/info/rfc4169>.
 [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
            Border Gateway Protocol 4 (BGP-4)", RFC 4271,
            DOI 10.17487/RFC4271, January 2006,
            <http://www.rfc-editor.org/info/rfc4271>.
 [RFC4283]  Patel, A., Leung, K., Khalil, M., Akhtar, H., and K.
            Chowdhury, "Mobile Node Identifier Option for Mobile IPv6
            (MIPv6)", RFC 4283, DOI 10.17487/RFC4283, November 2005,
            <http://www.rfc-editor.org/info/rfc4283>.
 [RFC4340]  Kohler, E., Handley, M., and S. Floyd, "Datagram
            Congestion Control Protocol (DCCP)", RFC 4340,
            DOI 10.17487/RFC4340, March 2006,
            <http://www.rfc-editor.org/info/rfc4340>.

Cotton, et al. Best Current Practice [Page 42] RFC 8126 IANA Considerations Section in RFCs June 2017

 [RFC4422]  Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple
            Authentication and Security Layer (SASL)", RFC 4422,
            DOI 10.17487/RFC4422, June 2006,
            <http://www.rfc-editor.org/info/rfc4422>.
 [RFC4446]  Martini, L., "IANA Allocations for Pseudowire Edge to Edge
            Emulation (PWE3)", BCP 116, RFC 4446,
            DOI 10.17487/RFC4446, April 2006,
            <http://www.rfc-editor.org/info/rfc4446>.
 [RFC4520]  Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
            Considerations for the Lightweight Directory Access
            Protocol (LDAP)", BCP 64, RFC 4520, DOI 10.17487/RFC4520,
            June 2006, <http://www.rfc-editor.org/info/rfc4520>.
 [RFC4589]  Schulzrinne, H. and H. Tschofenig, "Location Types
            Registry", RFC 4589, DOI 10.17487/RFC4589, July 2006,
            <http://www.rfc-editor.org/info/rfc4589>.
 [RFC4727]  Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
            ICMPv6, UDP, and TCP Headers", RFC 4727,
            DOI 10.17487/RFC4727, November 2006,
            <http://www.rfc-editor.org/info/rfc4727>.
 [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
            (TLS) Protocol Version 1.2", RFC 5246,
            DOI 10.17487/RFC5246, August 2008,
            <http://www.rfc-editor.org/info/rfc5246>.
 [RFC5378]  Bradner, S., Ed. and J. Contreras, Ed., "Rights
            Contributors Provide to the IETF Trust", BCP 78, RFC 5378,
            DOI 10.17487/RFC5378, November 2008,
            <http://www.rfc-editor.org/info/rfc5378>.
 [RFC5742]  Alvestrand, H. and R. Housley, "IESG Procedures for
            Handling of Independent and IRTF Stream Submissions",
            BCP 92, RFC 5742, DOI 10.17487/RFC5742, December 2009,
            <http://www.rfc-editor.org/info/rfc5742>.
 [RFC5771]  Cotton, M., Vegoda, L., and D. Meyer, "IANA Guidelines for
            IPv4 Multicast Address Assignments", BCP 51, RFC 5771,
            DOI 10.17487/RFC5771, March 2010,
            <http://www.rfc-editor.org/info/rfc5771>.
 [RFC5795]  Sandlund, K., Pelletier, G., and L-E. Jonsson, "The RObust
            Header Compression (ROHC) Framework", RFC 5795,
            DOI 10.17487/RFC5795, March 2010,
            <http://www.rfc-editor.org/info/rfc5795>.

Cotton, et al. Best Current Practice [Page 43] RFC 8126 IANA Considerations Section in RFCs June 2017

 [RFC6014]  Hoffman, P., "Cryptographic Algorithm Identifier
            Allocation for DNSSEC", RFC 6014, DOI 10.17487/RFC6014,
            November 2010, <http://www.rfc-editor.org/info/rfc6014>.
 [RFC6230]  Boulton, C., Melanchuk, T., and S. McGlashan, "Media
            Control Channel Framework", RFC 6230,
            DOI 10.17487/RFC6230, May 2011,
            <http://www.rfc-editor.org/info/rfc6230>.
 [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
            Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
            2011, <http://www.rfc-editor.org/info/rfc6275>.
 [RFC6698]  Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
            of Named Entities (DANE) Transport Layer Security (TLS)
            Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
            2012, <http://www.rfc-editor.org/info/rfc6698>.
 [RFC6709]  Carpenter, B., Aboba, B., Ed., and S. Cheshire, "Design
            Considerations for Protocol Extensions", RFC 6709,
            DOI 10.17487/RFC6709, September 2012,
            <http://www.rfc-editor.org/info/rfc6709>.
 [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
            Specifications and Registration Procedures", BCP 13,
            RFC 6838, DOI 10.17487/RFC6838, January 2013,
            <http://www.rfc-editor.org/info/rfc6838>.
 [RFC6895]  Eastlake 3rd, D., "Domain Name System (DNS) IANA
            Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,
            April 2013, <http://www.rfc-editor.org/info/rfc6895>.
 [RFC6994]  Touch, J., "Shared Use of Experimental TCP Options",
            RFC 6994, DOI 10.17487/RFC6994, August 2013,
            <http://www.rfc-editor.org/info/rfc6994>.
 [RFC7120]  Cotton, M., "Early IANA Allocation of Standards Track Code
            Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
            2014, <http://www.rfc-editor.org/info/rfc7120>.
 [RFC7564]  Saint-Andre, P. and M. Blanchet, "PRECIS Framework:
            Preparation, Enforcement, and Comparison of
            Internationalized Strings in Application Protocols",
            RFC 7564, DOI 10.17487/RFC7564, May 2015,
            <http://www.rfc-editor.org/info/rfc7564>.

Cotton, et al. Best Current Practice [Page 44] RFC 8126 IANA Considerations Section in RFCs June 2017

 [RFC7595]  Thaler, D., Ed., Hansen, T., and T. Hardie, "Guidelines
            and Registration Procedures for URI Schemes", BCP 35,
            RFC 7595, DOI 10.17487/RFC7595, June 2015,
            <http://www.rfc-editor.org/info/rfc7595>.
 [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
            S. Ray, "North-Bound Distribution of Link-State and
            Traffic Engineering (TE) Information Using BGP", RFC 7752,
            DOI 10.17487/RFC7752, March 2016,
            <http://www.rfc-editor.org/info/rfc7752>.
 [RFC8141]  Saint-Andre, P. and J. Klensin, "Uniform Resource Names
            (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
            <http://www.rfc-editor.org/info/rfc8141>.

Cotton, et al. Best Current Practice [Page 45] RFC 8126 IANA Considerations Section in RFCs June 2017

Acknowledgments for This Document (2017)

 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.
 Thank you to Amanda Baber and Pearl Liang for their multiple reviews
 and suggestions for making this document as thorough as possible.
 This document has benefited from thorough review and comments by many
 people, including Benoit Claise, Alissa Cooper, Adrian Farrel,
 Stephen Farrell, Tony Hansen, John Klensin, Kathleen Moriarty, Mark
 Nottingham, Pete Resnick, and Joe Touch.
 Special thanks to Mark Nottingham for reorganizing some of the text
 for better organization and readability, to Tony Hansen for acting as
 document shepherd, and to Brian Haberman and Terry Manderson for
 acting as sponsoring ADs.

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.

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 RFC 4288.

Cotton, et al. Best Current Practice [Page 46] RFC 8126 IANA Considerations Section in RFCs June 2017

Authors' Addresses

 Michelle Cotton
 PTI, an affiliate of ICANN
 12025 Waterfront Drive, Suite 300
 Los Angeles, CA  90094-2536
 United States of America
 Phone: +1-424-254-5300
 Email: michelle.cotton@iana.org
 URI:   https://www.iana.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
 United States of America
 Phone: +1 919 254 7798
 Email: narten@us.ibm.com

Cotton, et al. Best Current Practice [Page 47]

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