Guidelines for Writing an IANA Considerations Section in RFCs
draft-ietf-ianabis-rfc8126bis-04
| Document | Type | Active Internet-Draft (ianabis WG) | |
|---|---|---|---|
| Authors | Amanda Baber , Sabrina Tanamal | ||
| Last updated | 2026-10-26 | ||
| Replaces | draft-baber-ianabis-rfc8126bis | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-ianabis-rfc8126bis-04
Network Working Group A. Baber, Ed.
Internet-Draft S. Tanamal, Ed.
Obsoletes: 8126 (if approved) IANA
Intended status: Best Current Practice 26 October 2026
Expires: 29 April 2027
Guidelines for Writing an IANA Considerations Section in RFCs
draft-ietf-ianabis-rfc8126bis-04
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 fourth edition of this document; it obsoletes RFC 8126.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 29 April 2027.
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Copyright Notice
Copyright (c) 2026 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 (https://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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised 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 Up Front . . . . . . . . . . . . . . . 5
2. Creating New IANA Registries . . . . . . . . . . . . . . . . 8
2.1. Organization of Registries . . . . . . . . . . . . . . . 8
2.1.1. Naming Registries and Registry Groups . . . . . . . . 9
2.2. Documentation Requirements for Registries . . . . . . . . 9
2.3. Choosing a Registration Policy and Well-Known Policies . 11
2.3.1. Private Use . . . . . . . . . . . . . . . . . . . . . 14
2.3.2. Experimental Use . . . . . . . . . . . . . . . . . . 15
2.3.3. Hierarchical Allocation . . . . . . . . . . . . . . . 15
2.3.4. First Come First Served . . . . . . . . . . . . . . . 16
2.3.5. Expert Review . . . . . . . . . . . . . . . . . . . . 18
2.3.6. Specification Required . . . . . . . . . . . . . . . 19
2.3.7. RFC Required . . . . . . . . . . . . . . . . . . . . 22
2.3.8. IETF Review . . . . . . . . . . . . . . . . . . . . . 22
2.3.9. Standards Action . . . . . . . . . . . . . . . . . . 22
2.3.10. IESG Approval . . . . . . . . . . . . . . . . . . . . 23
2.3.11. With Expert Review . . . . . . . . . . . . . . . . . 23
2.3.12. Using the Well-Known Registration Policies . . . . . 24
2.3.13. Using Multiple Policies . . . . . . . . . . . . . . . 26
2.4. Example of an IANA Considerations Section . . . . . . . . 29
2.5. Specifying Change Control for Registries and
Registrations . . . . . . . . . . . . . . . . . . . . . . 30
2.5.1. Contacts as Change Control Representatives . . . . . 31
2.6. Registry Creation and Design Considerations . . . . . . . 31
2.6.1. Metadata . . . . . . . . . . . . . . . . . . . . . . 31
2.6.2. Registration Templates . . . . . . . . . . . . . . . 33
2.6.3. Module Files . . . . . . . . . . . . . . . . . . . . 33
2.6.4. URN Sub-Namespace Registries . . . . . . . . . . . . 34
2.6.5. Field-Specific Modification Procedures . . . . . . . 34
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2.6.6. Early Allocation . . . . . . . . . . . . . . . . . . 35
3. Maintaining, Managing, and Modifying Existing Registries . . 35
3.1. Registering and Updating Values in an Existing
Registry . . . . . . . . . . . . . . . . . . . . . . . . 36
3.1.1. Documentation Requirements for Registrations . . . . 36
3.1.2. Updating Existing Registrations . . . . . . . . . . . 38
3.1.3. Overriding Registration Procedures . . . . . . . . . 39
3.2. Revising Existing Registries . . . . . . . . . . . . . . 39
3.3. Closing, Obsoleting, and Deprecating Registries and
Registrations . . . . . . . . . . . . . . . . . . . . . . 40
3.4. Namespaces Lacking Documented Guidance . . . . . . . . . 41
3.5. After-the-Fact Registrations . . . . . . . . . . . . . . 41
3.6. Reclaiming Assigned Values . . . . . . . . . . . . . . . 42
3.7. What to Do in "bis" Documents . . . . . . . . . . . . . . 42
3.7.1. Organizing "bis" Considerations . . . . . . . . . . . 43
3.7.2. Handling Existing References . . . . . . . . . . . . 43
3.7.3. Describing Updates to IANA . . . . . . . . . . . . . 44
4. Designated Experts and Mailing List Reviews . . . . . . . . . 45
4.1. The Motivation for Designated Experts . . . . . . . . . . 45
4.2. The Role of the Designated Expert . . . . . . . . . . . . 45
4.2.1. Managing Designated Experts in the IETF . . . . . . . 47
4.3. Designated Expert Reviews . . . . . . . . . . . . . . . . 47
4.4. Expert Reviews and the Document Lifecycle . . . . . . . . 49
4.5. Mailing Lists . . . . . . . . . . . . . . . . . . . . . . 49
5. Well-Known Registration Status Terminology . . . . . . . . . 50
6. Documentation References in IANA Registries . . . . . . . . . 51
7. Appeals . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
8. IESG Responsibilities and Capabilities . . . . . . . . . . . 52
9. Language and Formatting in the IANA Considerations Section . 53
9.1. When There Are No IANA Actions . . . . . . . . . . . . . 54
10. Security Considerations . . . . . . . . . . . . . . . . . . . 54
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 55
11.1. Reference Updates . . . . . . . . . . . . . . . . . . . 55
11.2. Change Controller Fields . . . . . . . . . . . . . . . . 55
11.3. IESG-Recognized Standards-Related Organization
Registry . . . . . . . . . . . . . . . . . . . . . . . . 55
11.3.1. Registration Procedure . . . . . . . . . . . . . . . 56
12. Changes Relative to Earlier Editions of BCP 26 . . . . . . . 56
12.1. 2026: Changes in This Document Relative to RFC 8126 . . 56
12.2. 2016: Changes in This Document Relative to RFC 5226 . . 57
12.3. 2008: Changes in RFC 5226 Relative to RFC 2434 . . . . . 58
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 59
13.1. Normative References . . . . . . . . . . . . . . . . . . 59
13.2. Informative References . . . . . . . . . . . . . . . . . 59
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 66
A.1. Acknowledgments for This Document (2026) . . . . . . . . 66
A.2. Acknowledgments for the Third Edition (2017) . . . . . . 67
A.3. Acknowledgments from the Second Edition (2008) . . . . . 67
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A.4. Acknowledgments from the First Edition (1998) . . . . . . 67
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 67
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 coordinated by a central
record keeper known as the Internet Assigned Numbers Authority (IANA)
[RFC2860]. Registries for the protocol field in the IP header
[RFC0791] and media types [RFC6838] are two examples of such
coordination.
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". All Internet-
Drafts must include this section.
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.
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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, or
instructions to, 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 at https://iana.org/help/protocol-
registration 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.
1.3. A Quick Checklist Up Front
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 (see Section 4.3). 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 3.1.3). See Section 8 for more information on IESG
responsibilities.
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4. Contact IANA if you have any questions about writing an IANA
Considerations section. In particular, contact IANA if your
document may need special IANA resources, such as if IANA would
have to host a new type of module, or coordinate with another
organization, or process a high volume of registration requests,
and so on.
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 the registry group that it should be part of (see
Section 2.1). Your document might create a new registry group;
that would need to be called out separately from the creation of
the registries in the group.
3. Clearly specify the information 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 Section 2.5).
6. Select a registration policy -- or a set of policies -- to use
for future registrations (see Section 2.3, and especially note
Sections 2.3.12 and 2.3.13).
7. If you're using a policy that requires a designated expert
(Expert Review or Specification Required), understand Section 4
and provide review guidance to the designated expert (see
Section 4.3).
8. If any items or ranges in your registry need to be reserved for
special use or are otherwise unavailable for assignment, see
Section 5.
If you are registering into an existing registry...
1. Clearly identify the registry by its exact name and optionally by
its URL (see Section 3.1.1).
2. If the registry has multiple ranges from which assignments can be
made, make it clear which range is requested (see Section 3.1.1).
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3. Unless an early allocation has already been secured, avoid using
specific values for numeric or bit assignments, and let IANA pick
a suitable value at registration time (see Section 3.1.1). This
will avoid registration conflicts among multiple documents.
4. If you need an early assignment during document development, see
[RFC7120]. If the registry does not require RFC publication, you
can request values from IANA directly without invoking the
process from RFC 7120.
5. 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 text (see Sections 3.1.1 and 6).
6. Use both the IANA website and the registry's reference
document(s) to determine what the registry requires so you can
accurately provide all the necessary information (see
Section 3.1.1). In particular, documents published after the
original one may add fields, change the registration
requirements, or other such actions that would affect your
registration.
7. Similarly, check for any special registry-specific rules or
processes, such as posting to a particular mailing list for
comment (see Section 3.1.1).
8. If the registration policy for the registry does not already
dictate the change control policy, make sure to make the change
control policy clear, in case the registration needs to be
updated or modified later (see Section 2.5).
If you're writing a "bis" document or otherwise making older
documents obsolete, see Section 3.7.
If you need to change the format/contents or policies for an existing
registry, see Section 3.2.
If you need to update an existing registration, see Section 3.1.2.
If you need to close down a registry because it is no longer needed,
see Section 3.3.
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2. Creating New IANA Registries
Defining a registry involves describing the namespaces to be created,
listing an initial set of assignments (if applicable), and
documenting guidelines for future assignments. The subsections below
describe registry creation requirements, issues, and common
approaches.
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, 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.
2.1. Organization of Registries
All registries are anchored from the IANA "Protocol Registries" page
at 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.
Registry A collection of entries whose assigned, available, and/or
reserved values are presented in a single table. Entries in the
table may also be referred to as "assignments", "allocations"
(that is, allocations from a pool of values), or "registrations"
(a term that is more commonly applied to strings). Entries
consist of at least an identifier and a reference to a
specification and/or one or more responsible parties.
Registry group A set of related registries that share a common URL.
When creating a registry, document authors must tell IANA which
registry group it belongs in, citing the name of the group and the
URL. If no suitable group exists, the document must create one.
While most protocols require only a single registry group (which
is typically named for the protocol and its abbreviation),
multiple groups might be appropriate.
Subregistry A registry "for" one or more registrations in a parent
registry. Examples include "Error Code 1 Subcodes," a subregistry
for value 1 ("Common Header Parse Error") in the "GIST Error
Codes" registry [RFC5971], and "Code Values for RADIUS Attribute
241.1, Frag-Status" [RFC7499].
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In the past, documents have sometimes referred to registry groups as
"top-level registries," or referred to the groups as "registries" and
called all of the tables within them "subregistries." However, the
term "subregistry" is more useful as an indicator of a parent-child
relationship between registries, and "top-level registry" suggests a
sort of permanence or natural order that doesn't reflect the fact
that the IESG can choose to reorganize those groups. With AD
approval, IANA can move registries and expand or delete groups,
leaving tombstones and pointers as appropriate. (If one URL replaces
another, IANA will make sure the original will always redirect to the
new one.)
2.1.1. Naming Registries and Registry Groups
IANA strongly prefers that the registry of "Foo" types be named
simply "Foo Types", rather than "Foo Type Registry". A registry
group for the BAR protocol should be named "Beyond All Recognition
(BAR)" rather than "BAR Parameters." An exception for the former
might be made when, for example, several widely-used unofficial
versions of the registry exist outside the IETF. In that case, it
might be useful to indicate that the version on the IANA website is
the official one.
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:
Registry name
This name will appear on the IANA web page and will be referred to
in future documents that allocate values from the new space. The
full name (which can include an acronym) must be provided; you
cannot leave this to IANA to determine.
It is highly desirable that the name not be easily confused with
the name of another registry. IANA's preferred solution is to use
the protocol name as a prefix if possible. Examples of registries
that use this naming pattern include "TLS Cipher Suites", "MASQUE
URI Suffixes", and "HTTP/2 Settings". Each of these is part of a
registry group that includes the protocol in its name.
In most cases, the registry name should not include the word
"registry."
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Registry group name
When creating a registry, the group that it is a part of must be
identified by its full name. See Section 2.1. Providing a URL
that precisely identifies that group helps IANA understand the
request.
The registry group name should not include the words "parameters"
or "registries."
Size, format, and syntax of registry entries
Which fields to record in the registry, any limits on field
content, and the exact format in which registry values should be
displayed.
For numeric assignments, authors should indicate at least the
following information:
* the range of available values (including upper and lower bound)
* whether values are to be recorded in decimal, hexadecimal, or
some other format
* whether specific values can be requested (for "First Come First
Served" registries)
When the registered identifier is a string, authors should specify
the following:
* whether case matters
* any limits on length
* any limits on eligible ASCII characters
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 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.
Applicable registration policy
The policy that will apply to all future requests for
registration. See Section 2.3.
Required information for registration
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The information applicants must include in their registration
requests.
Some registries require as little as a request for a value and a
reference to the document that defines it (or in the absence of a
document, contact information for a responsible party). Other
registries require a detailed registration template that describes
security considerations, internationalization considerations, or
other relevant information.
If a field can be filled in with "N/A," like the "Required
Parameters" section in a media type registration template, or if a
field is limited to a specific set of entries, like the "Abstract
Data Type" field in the IPFIX Information Elements registry, the
document should indicate this.
When registration requires a template, consider whether the
registry itself should display all of the fields in the template,
only certain fields, or selected fields and a link to the
registrant's template (typically a plain-text document hosted on
the IANA website). Examples of the latter approach include the
URI scheme [RFC7595] and media type [RFC6838] registries (at the
time this document is published).
Initial assignments and reservations
The document must include the initial contents of new registries,
and they should appear in the IANA Considerations section. While
requests to assign numeric values from existing registries should
be described as "TBD1," "TBD2," etc., until IANA allocates them,
new registries that consist of numeric value assignments must
specify the initial values.
In addition, the document must identify any values (numeric or
otherwise) or value ranges that should be marked "Reserved,"
"Reserved for Private Use," or "Reserved for Experimental Use"
(see Section 5).
For an example of an IANA Considerations section that registers a
value and creates a registry, see Section 2.4.
2.3. Choosing a Registration Policy and Well-Known Policies
%% NOTE FOR IANABIS: %%
Remaining Specification Required issues:
* Waiting for [I-D.nottingham-ianabis-spec-reqd] discussion.
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* Determine procedure(s) for assigning sub-policies to existing
Specification Required registries.
FCFS/Spec hybrid:
* The charter calls for "a registration policy between 'First Come
First Served' and 'Specification Required'" that would work for
registries where a lightweight specification that DOESN'T need
technical review should be required, but a version of this called
"First Come First Served With URL" was initially rejected. The
impression we received in Montreal is that such a procedure would
be useful, but it needs a better name.
%% END NOTES %%
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.
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:
* 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).
* 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). IANA cannot
review requests or specifications for technical content.
Perhaps most importantly, unreviewed extensions can impact
interoperability and security. See [RFC6709].
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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
receives all of the information necessary to screen requests without
the application of technical expertise or 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.
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
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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 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
(or both) 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 2.3.13.
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]
2.3.1. 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:
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Site-specific options in DHCP [RFC2939]
Fibre Channel Port Type Registry [RFC4044]
TLS ClientCertificateType Identifiers 224-255 [RFC5246]
2.3.2. 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]
2.3.3. 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:
* 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.
* Object Identifiers - defined by ITU-T recommendation X.208.
According to the informal site at http://www.alvestrand.no/
objectid, some registries include
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- 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.
* URN namespaces - IANA registers URN Namespace IDs (NIDs
[RFC8141]), and the organization registering an NID is responsible
for allocations of URNs within that namespace.
Hierarchical Allocation is not a policy for obtaining values from
IANA, but for obtaining values from a registrant that has already
received an allocation from IANA.
2.3.4. 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, the registry
must require at least the following, in addition to any other
registry-appropriate information:
* a point of contact (including an email address)
* a change controller (See 2.5)
* a label or brief description of how the value will be used
It is 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]
2.3.4.1. When to Consider First Come First Served
The First Come First Served procedure streamlines the registration
process, but because it doesn't allow for any real filtration,
special care should be taken before selecting it.
Reasons to use First Come First Served:
* Numeric value exhaustion isn't a concern
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* Any well-formed registration would be acceptable, regardless of
registrant, content, or purpose
* A low bar to entry would encourage registration
Reasons to choose a different procedure:
IANA can perform limited, non-semantic checks. That is, if the IANA
Considerations section requires it, IANA can check for
characteristics like the following:
* Illegal characters
* Correct hexadecimal representation of characters
* A specification URL, if desired, that resolves (and does not serve
obviously abusive content)
However, IANA staff cannot review registration proposals for issues
like these:
* String is too generic
* Specification claims to address a topic, but does not
* Mismatch between applicant and request (IANA can flag this and
approach the IESG for advice, but may not have enough context to
be aware of any issue)
2.3.4.1.1. FCFS and Strings
Registries of strings can be particularly vulnerable to a "land
rush," in which IANA receives an unusually large number of requests
to register values that have been newly identified as desirable. In
the absence of an expert review or an RFC publication requirement,
IANA generally has no way to reject well-formed First Come First
Served requests.
For some string registries, conservation may not be a concern. But
if any potential combination of registrant and string(s) could be
problematic (for example, if an individual were to register “ai,”
“bank,” and “x”), the First Come First Served procedure should not be
used. Registration should instead require expert approval, and the
document should give experts citable evaluation criteria. For an
example, see Section 3.8 of [RFC7595].
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2.3.4.1.2. FCFS and Specifications
First Come First Served registries can require that the applicant
provide a specification. However, if that specification needs to be
checked for any quality other than availability, the First Come First
Served procedure is not appropriate, and the Specification Required
procedure (which includes an expert review) should be used instead.
Specification Required is not necessarily a restrictive procedure.
If a lightweight review is sufficient, the document's instructions to
the designated experts should explain that the request only needs to
be checked for some characteristic(s).
%% NOTES FOR IANABIS: Reference to sub-policy in
[I-D.nottingham-ianabis-spec-reqd] likely to be added here. %%
2.3.4.2. FCFS Code Point Change Concerns
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. IANA
cannot review change requests for content, but will check that the
request has been authorized by the change controller's listed contact
or the change controller itself, and the change controller should
not, in most cases, be requesting incompatible changes nor
repurposing a registered code point. See also Sections 3.6 and 2.5.
A working group or any other entity 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).
2.3.5. Expert Review
For the Expert Review policy, review and approval by a designated
expert (see Section 4) 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".)
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The document must provide clear guidance for the designated expert,
ideally in a dedicated subsection that describes documentation
requirements (if any) and review criteria. 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 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 4 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
IANA will add a change controller field to all registries that use
the Expert Review procedure. See Section 2.5.
Examples:
EAP Method Types [RFC3748]
HTTP Digest AKA algorithm versions [RFC4169]
URI schemes [RFC7595]
GEOPRIV Location Types [RFC4589]
2.3.6. Specification Required
%% NOTES FOR IANABIS: this procedure should be defined in
[I-D.nottingham-ianabis-spec-reqd], but some information will likely
be retained here (e.g., information about experts). No changes in
version -04, though. %%
For the Specification Required policy, review and approval by a
designated expert (see Section 4) 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.
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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
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 4.4).
As with Expert Review (Section 2.3.5), clear guidance to the
designated expert should be provided when defining the registry, and
thorough understanding of Section 4 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]
2.3.6.1. Common Specification Issues
The subsections below describe approaches to common specification
eligibility issues.
2.3.6.1.1. Internet-Drafts as Specifications
The working group or document that creates a "Specification Required"
registry can declare that Internet-Drafts qualify for permanent
registration within that registry. In the absence of such a
declaration, however, Internet-Drafts are not eligible for permanent
"Specification Required" registration. IETF stream Internet-Drafts
can obtain temporary-but-renewable early allocations regardless, as
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described in [I-D.ietf-ianabis-rfc7120bis], but that process is not
available to Internet-Drafts published in other streams.
If a Designated Expert feels that an existing registry (or set of
related registries) should be modified to allow I-Ds as valid
specifications, they should consult with the relevant Area Directors.
%% QUESTIONS/NOTES FOR IANABIS: this section needs 1) reasons WGs
should/shouldn't consider making I-Ds eligible for permanent
registration and, probably, 2) information about how a WG can declare
I-Ds eligible. Is an RFC required? If the registry has already been
created, can the expert/chairs simply poll the WG? Should IANA
record decisions to allow I-Ds in Specification Required registries?
%%
2.3.6.1.2. Purchase-Only Specifications
If obtaining the specification requires a fee, the organization must
provide a free copy for the expert to review. However, if the expert
considers a purchase-only specification inappropriate for that
registry or proposed registration, the expert can reject the request
and require a freely-available specification.
2.3.6.1.3. Publication Requirements for Non-IETF Standards
The "Specification Required" policy requires both IESG-designated
expert approval and a permanent and readily available public
specification, but some standards-related organizations may be unable
to publish any version of a specification until they receive code
point assignments. [I-D.ietf-ianabis-rfc7120bis] proposes a policy
that can make early allocations available to those organizations,
provided the expert believes the allocation is appropriate and the
IESG recognizes the source of the specification as a standards-
related organization. For more information, see Section 2.3 of that
document.
2.3.6.2. Procedure-Specific IANA Considerations Text
Because the procedure includes expert review, an IANA Consideration
that creates a Specification Required registry must include guidance
for the designated experts, as described in Section 2.3.5. If the
document is creating multiple registries, guidance could be collected
in a single subsection.
If Internet-Drafts should be eligible for permanent registration (as
opposed to the time-limited, renewable early allocation available to
IETF stream I-Ds), the IANA Considerations section should declare
this.
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2.3.7. 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]
2.3.8. 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
[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]
Accounting-Auth-Method AVP values in DIAMETER [RFC4005]
TLS Extension Types [RFC5246]
2.3.9. Standards Action
For the Standards Action policy, values are assigned only through
Standards Track or Best Current Practice RFCs in the IETF Stream.
Examples:
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BGP message types [RFC4271]
Mobile Node Identifier option types [RFC4283]
TLS ClientCertificateType Identifiers 0-63 [RFC5246]
DCCP Packet Types [RFC4340]
2.3.10. 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 fallback
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.
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:
Assigned Internet Protocol Numbers [RFC5237]
IPv4 IGMP Type and Code values [RFC3228]
Mobile IPv6 Mobility Header Type and Option values [RFC6275]
2.3.11. With Expert Review
IANA does not ordinarily ask IESG-designated registry experts to
review requests for registration in "Standards Action," "IETF
Review," "RFC Required," and "IESG Approval" registries. If a
registry requires both expert review and either RFC publication or
IESG approval, the following expert-augmented hybrid procedures are
available:
* Standards Action With Expert Review
* IETF Review With Expert Review
* RFC and Expert Review Required
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* IESG Approval With Expert Review
As described in Section 4.4, IANA will initiate the expert review
request during IETF Last Call or, if applicable, the document's
conflict review. If the IESG and the expert disagree, the IESG can
choose to override the expert.
If the submission is intended for direct approval for the IESG, as
described in Section 8, IANA will submit the request to both the
expert and the IESG.
Most registries that require RFC publication do not require an
additional expert review. An expert-augmented procedure might be
appropriate, however, if registry designers want to be sure that a
specialist checks every proposal for intra-registry consistency.
Examples:
* "ACE Groupcomm Policies" [RFC9594]
* "Option Codes" (DHCPv6) [RFC8415]
2.3.11.1. Procedure-Specific IANA Considerations Text
An IANA Consideration that creates any expert-dependent registry must
include guidance for the designated experts, as described in
Section 2.3.5. If the document is creating multiple registries,
guidance could be collected in a single subsection.
2.3.12. 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.
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The well-known policies from "First Come First Served" to "Standards
Action" specify a range of policies in increasing order of review
requirements:
+==================+=========================+======================+
| Policy | Description | Review Level |
+==================+=========================+======================+
| First Come First | Not reviewed for | Minimal |
| Served (FCFS) | technical content. | |
+------------------+-------------------------+----------------------+
| Expert Review | Expert review | Moderate |
| | required. | |
+------------------+-------------------------+----------------------+
| Specification | Expert review + | Moderate (equivalent |
| Required | public specification. | to Expert Review) |
+------------------+-------------------------+----------------------+
| RFC Required | RFC publication (any | High |
| | stream). | |
+------------------+-------------------------+----------------------+
| IETF Review | RFC publication in | Higher |
| | IETF Stream. | |
+------------------+-------------------------+----------------------+
| Standards Action | RFC publication in | Highest |
| | Standards Track or | |
| | BCP. | |
+------------------+-------------------------+----------------------+
Table 1
Examples of situations that might merit IETF Review or Standards
Action include the following:
* 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.
* 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.
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* When there are security implications with respect to the resource,
a 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.
2.3.13. Using Multiple Policies
If some assignments within a registry should be easier to obtain than
others, multiple registration procedures may be appropriate.
For example:
* In large numeric registries, stricter procedures can apply only to
the most desirable ranges.
* If registration is intended for the IETF or other SDOs but not
individuals, the process can depend on the submitter.
* When the values are strings or some entries are "provisional," a
field or label can indicate the review level for each
registration.
2.3.13.1. Range-Dependent Policies
The most common application for multiple registration policies is to
make assignments from different ranges of numeric values more or less
difficult to obtain. For example, if a registry's available values
range from 0-65535, authors might assign a strict registration policy
to values 0-255 and one or two relatively lightweight policies (like
First Come First Served) to the remaining values. (Along with an
Experimental or Private Use reservation, if appropriate.)
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2.3.13.2. Separate Requirements for IETF and Non-IETF Specifications
If IETF registrants should be required to produce an RFC, or a
certain type of RFC, but registration should still be open to
standards produced by organizations outside the IETF, two approaches
are available:
* A single "Specification Required" policy that applies to all
requests. This adds overhead for RFC-based registrations, which
do not ordinarily require review by a designated expert, but would
be subjected to one here. In addition, this policy would open
registration to every RFC stream and type, which may not be the
intention.
* Two policies that apply to the same set of available values: "IETF
Review" or "Standards Action" for registrations made via the IETF
process (or "RFC Required," if other streams are also
appropriate), and "Specification Required" for requests submitted
by other organizations. Any issues concerning submitter or
specification eligibility should be described in the instructions
to the expert.
2.3.13.3. Provisional and Permanent Registrations
Some existing registries have policies that allow provisional
registration: see URI Schemes [RFC7595] and Message 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
right for that registry as well. See QUIC Frame Types [RFC9000].
The provisional option can be implemented by splitting the registry
into separate "Permanent" and "Provisional" registries or by adding a
"Status" field (or similar) that can be filled in with a "Permanent"
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or "Provisional" label. You might also consider whether provisional
registrations should be accompanied by links to plain-text
registration templates, given that they're less likely to be
documented in RFCs, or whether certain registry fields should apply
only to one type of registration.
2.3.13.4. Two-Tiered Registries
When the registry needs to allow both IETF-reviewed and "simple"
(e.g., First Come First Served) registrations, but 1) the
registrations consist of strings rather than numeric values, 2) the
level of review cannot be indicated by the content of the strings
(e.g., the strings cannot be prefixed with "x-" or "vnd."), and 3) it
isn't appropriate to describe the simple registrations as
"Provisional," one of these two methods might be used:
* Create separate registries, each of which indicates the level of
review in its title: "IETF-Approved Fruit Strings," for example,
and "First Come First Served Fruit Strings."
* Create a registry that uses a dedicated field, like the "Status"
field in the provisional/permanent registry model, to indicate the
level of review applied to the registration. This field might be
called something like "RegAuth," and it could be filled in with
values like "IETF" and "Simple" (or "Informal" or "Non-IETF").
An "IETF" registration could use any procedure that requires an IETF
stream document: Standards Action, IETF Review, a bespoke process
that requires an IETF stream document as its base (for example, a
process that requires or forbids a certain type of RFC, such as
Informational), or one of those procedures with an Expert Review add-
on.
The IANA Considerations section could use text like this:
| This registry is open to both IETF-reviewed registrations and
| "simple" registrations that are not reviewed for technical
| content. The registry's "RegAuth" field will describe each
| registration as "IETF" or "Simple."
|
| The following RFC 8126 registration procedures will be applied
| to "IETF" and "Simple" registrations:
|
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| +=========+=========================+
| | RegAuth | Registration Procedure |
| +=========+=========================+
| | IETF | Standards Action |
| +---------+-------------------------+
| | Simple | First Come First Served |
| +---------+-------------------------+
|
| Table 2
|
| The registry will list IETF registrations first.
This approach could also be used to mark registrations that received
some other level of review, such as review by a designated expert.
Alternatively, IETF/non-IETF entries could be distinguished by
omitting the RegAuth field and placing the Change Controller field in
a prominent location in the table.
2.4. Example of an IANA Considerations Section
The example below requests an assignment from an existing registry
and creates a subregistry (as defined in Section 2.1) for that
assignment.
| X. IANA Considerations
|
| This document registers a FooBar option and creates a
| subregistry for that option.
|
| X.1. FooBar Option
|
| This document defines a new FooBar option called "Foo" (see
| Section F) and assigns value TBD1 from the "FooBar Options"
| registry [RFCXYZ] in the "FooBar" registry group [IANA-
| REGISTRY-REF]. The value should be allocated from the
| registry's "Specification Required" range.
|
| +=======+========+===============+===========+
| | Value | Name | Description | Reference |
| +=======+========+===============+===========+
| | TBD1 | FooBar | FooBar server | this RFC |
| +-------+--------+---------------+-----------+
|
| Table 3
|
| X.2. FooBar FooType Registry
|
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| The Foo tag (TBD1) also defines an 8-bit FooType field. IANA
| will create a new registry titled "Foo FooTypes" in the
| "FooBar" registry group [IANA-REGISTRY-REF].
|
| The registration procedure for future assignments is Expert
| Review [BCP26]. Initial values for the DHCP FooBar FooType
| registry are listed below.
|
| +=========+==============+======================+
| | Value | Name | Reference |
| +=========+==============+======================+
| | 0 | Reserved | RFCXXXX |
| +---------+--------------+----------------------+
| | 1 | Frobnitz | RFCXXXX, Section F.1 |
| +---------+--------------+----------------------+
| | 2 | NitzFrob | RFCXXXX, Section F.2 |
| +---------+--------------+----------------------+
| | 3-250 | Unassigned | |
| +---------+--------------+----------------------+
| | 251-254 | Reserved for | RFCXXXX |
| | | Private Use | |
| +---------+--------------+----------------------+
| | 255 | Reserved | RFCXXXX |
| +---------+--------------+----------------------+
|
| Table 4
|
| X.2.1. Guidance for Designated Experts
|
| The designated expert is expected to [...]
For examples of documents that establish registries, consult
[RFC9546], [RFC9516], and [RFC9454].
2.5. Specifying Change Control for Registries and Registrations
Registry definitions and registrations within registries often need
to be changed after they are created. The process of making such
changes can be complicated when the registry doesn't identify the
party authorized to approve them.
By default, change control for registries and registrations that
originate with IETF stream RFCs lies with the IETF, via the IESG.
IETF stream registrations that need to populate a registry's "Change
Controller" field should name the IETF rather than the IESG, except
where the reference document for a registry requires that the IESG be
named as the change controller instead (as in the port [RFC6335] and
IETF XML [RFC3688] registries, among others).
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IANA will add a "Change Controller" field to all registries that
don't require an IETF stream RFC for registration (i.e., "First Come
First Served", "Expert Review", "Specification Required", and "RFC
Required" registries). Authors can also initialize "IETF Review" and
"Standards Action" registries with a "Change Controller" field if
they anticipate that a future IETF stream document might make an
assignment on behalf of another change controller.
All registries created by documents outside of the IETF Stream should
specify a change controller for the registry itself and instruct IANA
to note the identity of that change controller at the top of the
registry. Documents that come from the Independent Submissions
stream may require special handling; see [RFC8726]. As of this
writing, no special instructions have been declared for registries
created by other streams.
2.5.1. Contacts as Change Control Representatives
IANA typically lists a public contact for "First Come First Served"
and "Expert Review" registrations, among others. While these
contacts are available, they may be treated as representatives of the
change controller.
2.6. Registry Creation and Design Considerations
The purpose of this section is to make authors aware of common
registry design practices that they might not have seen before and
point out issues that may require special handling.
2.6.1. Metadata
"Status," "Recommended," and "Notes" fields are often added to
registries after they've been created. Creating one (or more) before
the need becomes apparent not only saves time, but can prompt future
applicants, experts, and authors to add useful information that they
otherwise might not have seen a place for.
2.6.1.1. "Status" Field
In some cases, it may be useful to include a "Status" field that
reflects the operational or administrative state of each entry.
However, there is currently no single agreed-upon set of possible
status entries. Some registries use this field to indicate whether
registrations should be considered "provisional," "permanent,"
"deprecated," or "obsolete," although the last two states are more
often added to a registration's name or description field.
Examples of registries that use a "Status" field:
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https://www.iana.org/assignments/email-auth
https://www.iana.org/assignments/message-headers
https://www.iana.org/assignments/rsip-parameters
2.6.1.2. "Recommended" Field
If it's appropriate to indicate whether registered items are
recommended, consider whether "yes" and "no" answers are sufficient.
It might also be appropriate to add a note to the registry that
describes the meaning and/or limitations of each possible state. For
example, the "Recommended" field in the TLS Cipher Suites registry
can be filled in with one of three values: briefly, "Y" for "yes";
"N," which can mean only that review or applicability has been
limited, not that use is broadly discouraged; or "D," which does
discourage use. [RFC9847] defines those options in greater detail
and provides a note to be added to each affected registry.
Fields of this type can also be used to indicate whether usage is
required, or whether a recommendation is context-specific. Examples
include the "Use for DNSSEC Signing" and "Implement for DNSSEC
Signing" fields, among others, in the "DNS Security Algorithm
Numbers" registry updated by [RFC9904].
Examples:
https://www.iana.org/assignments/tls-parameters
https://www.iana.org/assignments/dns-sec-alg-numbers
2.6.1.3. Registration Notes
IANA recommends adding a "Notes" field to any registry. Designated
experts and Area Directors can approve updates to any registration's
"Notes" field, even when modifying other aspects of the registration
requires a specification.
2.6.1.4. Registry Notes
Notes attached to the registry itself (as opposed to notes attached
to individual registrations) are often supplied by RFCs, but can also
be added to the registry after publication, if the need becomes
apparent.
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When determining whether to add a note, consider whether some
alternative or future action might be called for, either in addition
to or instead of a note. For example, if a note should be used to
list the values that could appear in a field, consider who would be
responsible for updating that note if the list were to change. In
some cases, it could be appropriate for an RFC to list those values
instead, or even create a registry for them.
2.6.2. Registration Templates
In some cases, an appropriate registration template can require
applicants to fill in more fields than a table can easily display.
If all of the template information should be published, IANA could
post it as a text file and add link it to the registration. Examples
include media type and provisional URI scheme registrations:
https://www.iana.org/assignments/media-types
https://www.iana.org/assignments/uri-schemes
2.6.3. Module Files
IANA hosts MIB, YANG, and SID module files. If hosting a new type of
module would be useful and possible, the RFC should provide answers
to at least the following questions:
* Can modules be updated after creation, or would they be replaced?
* Will IANA update the module in accordance with registrations,
modifications, and/or status changes? IANA-specific instructions
should be included in or referenced from the IANA Considerations
section. (Note that IANA likely would not have expertise in this
area.)
* Do authors or IANA need to be aware of special considerations for
revision statements, references, or other fields? For example, if
a module includes reference information that appears in an
underlying First Come First Served registry, how would that module
treat a reference that consists solely of a name and contact
information?
* How will modules be validated?
* IANA typically performs registry actions when a document is sent
to the RFC Editor for processing, but posts new YANG modules after
RFC publication. How and when will these modules be provided to
IANA?
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2.6.3.1. YANG Modules
For information concerning YANG module creation and maintenance, see
[RFC9907], "Guidelines for Authors and Reviewers of Documents
Containing YANG Data Models."
2.6.4. URN Sub-Namespace Registries
Documents that request creation of a registry associated with a sub-
namespace under the IETF URN namespace occasionally misidentify the
desired sub-namespace and neglect to define registration requirements
within it.
Typically, specification authors will want to request a registry
under the "IETF URN Sub-namespace for Registered Protocol Parameter
Identifiers" registry [RFC3553], in which case the URN sub-namespace
would take the form "urn:ietf:params:foo", and the parameter URNs
assigned in the sub-namespace registry would take the form
"urn:ietf:params:foo:bar" or "urn:ietf:params:foo:bar:baz" (etc.). A
number of such registries already exist, and authors should check the
"Uniform Resource Name (URN) Namespace for IETF Use" registry group
(https://www.iana.org/assignments/params) to determine whether the
parameters they wish to register belong in an existing registry or
whether a new registry is required.
Less commonly, authors might wish to register an identifier in the
"IETF URN Sub-namespaces" registry [RFC6924] itself (rather than in
the protocol parameters sub-namespace), in which case the URN would
take the form "urn:ietf:foo". For the avoidance of doubt, sub-
namespaces in the IETF namespace are registered directly with IANA
via IETF Review, whereas new URN namespaces outside the IETF
namespace are registered into the URN namespaces registry
(https://www.iana.org/assignments/urn-namespaces)via Expert Review,
as described in [RFC8141], and therefore usually do not require
publication of an RFC with an IANA Considerations section.
2.6.5. Field-Specific Modification Procedures
If necessary, a separate registration procedure (Section 2.3) can be
applied to a single field. Typically, this field-specific procedure
will be less strict than the procedure required to receive an
assignment.
This approach could be useful in scenarios like these:
* A new column in a registry that requires RFC publication will have
to be backfilled, but the requirement isn't urgent, and the
information has yet to be compiled. If other parties are
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amenable, assigning the "Expert Review" procedure to the column
would make it possible to populate that column later without
producing another RFC.
* Registrants may need to update a "Date" column in a registry that
ordinarily requires expert approval. Because this is considered a
trivial update, modifications to that field could be implemented
by IANA on a First Come First Served basis, as in the "QUIC
Versions" registry [RFC9000].
* Alternatively, while codepoints with "Recommended" values
initially set to "N" might be registered via a procedure like
Specification Required, changing that value to "Y" might require
an RFC published in the IETF Stream.
2.6.6. Early Allocation
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, such as when
early implementations are created while the document is still under
development.
IANA has mechanisms for handling such early allocations in some
cases. See [I-D.ietf-ianabis-rfc7120bis] for details. It is not
necessary to explicitly mark a registry as allowing early allocation,
because the general rules will apply.
However, if early allocation is not appropriate for a "Specification
Required" registry, or for any registry that requires RFC
publication, IANA should be instructed to attach a note that says,
"The time-limited early allocation policies described by
[I-D.ietf-ianabis-rfc7120bis] do not apply to this registry."
2.6.6.1. Early Registry Creation
Early registry creation is available to available to working groups
(and, with AD approval, to AD-sponsored documents) that need to
coordinate allocations for other documents or organizations. That
procedure is described in [I-D.ietf-ianabis-early-registries].
3. Maintaining, Managing, and Modifying Existing Registries
The subsections below describe requirements for documenting registry
changes in an IANA Considerations section. Changing a registry could
mean registering a value, changing some aspect of an existing
registration record, or updating the registry's rules or structure.
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3.1. Registering and Updating Values in an Existing Registry
RFCs that allocate values or update existing registrations must
document those changes in the document's IANA Considerations section.
3.1.1. Documentation Requirements for Registrations
Documents often need to request an assignment from an existing
registry (one created by a previously-published document).
To clearly identify the registry, the document should do the
following:
* Use the exact registry name as listed on the IANA web page
* Cite the RFC that defines the registry
* Provide the URL for the registry (see Section 2.2)
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.
There is no need to mention what the registry's assignment policy is,
as that should be clear from the references. However, if multiple
assignment policies might apply, as in registries that have different
policies for different ranges, 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.
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.
3.1.1.1. Registering Numeric Values
I-Ds must not specify numeric values before IANA allocates them.
Instead, placeholders such as "TBD1" and "TBD2" should be used
consistently throughout the document, giving each item to be
registered a different placeholder. The RFC Editor will replace
placeholder names with the IANA-assigned values.
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Exceptions should be made only when a document or working group has
established a registry-specific or protocol-specific method for
claiming unassigned values. However, IANA will not reserve those
unallocated values in advance and cannot guarantee their assignment.
Normally, numeric values are chosen by IANA when the IESG approves
the document. When authors need to specify numeric values for
testing or early implementations, they should either request early
allocation (this request must be submitted by a working group chair
or Area Director; see Section 2.6.6) or use values that have already
been set aside for testing or experimentation (if the registry in
question allows doing so without an explicit assignment).
3.1.1.2. Registering Text Values
Text-string values are typically 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. However, when drafts need to specify string values
for testing or early implementations, it is often useful to use a
draft value, possibly including the draft version number, instead of
the expected final value. 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.
3.1.1.3. How to Request Assignments in an IANA Considerations Section
As an example, the following text could be used to request an
assignment from the "Fruit Codes" registry:
IANA has assigned value TBD1 to "Banana" in the "Fruit Codes"
registry defined by Section 3.1 of RFC X.
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:
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+=======+=============+=======================+
| Value | Description | Reference |
+=======+=============+=======================+
| TBD1 | Pineapple | this RFC, Section 3.2 |
+-------+-------------+-----------------------+
| TBD2 | Starfruit | this RFC, Section 3.3 |
+-------+-------------+-----------------------+
| TBD3 | Banana | this RFC, Section 3.4 |
+-------+-------------+-----------------------+
Table 5
If the authors feel that including the full table of changes is too
verbose or repetitive, the IANA Considerations section could point to
an appendix that contains the table.
3.1.2. 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, media types and URN namespaces [RFC8141] 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:
* Letting registrants and/or nominated change controllers update
their own registrations, subject to the same constraints and
review as with new registrations.
* Allowing attachment of comments to the registration, as with a
"Notes" or "Comment" field (Section 2.6.1.3). This can be useful
in cases where others have significant objections to a
registration, but the author does not agree to change the
registration.
* Designating the IETF (as represented by 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 ensures that necessary updates can
be made even if the original registrant cannot be reached.
Unless otherwise specified, the following will hold true:
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* The applicable registration procedure will also serve as the
modification procedure.
* Unless the registration was made by an RFC, IANA can confirm and
approve requests to update contact and change controller
information. However, IANA may request advice from experts or
Area Directors.
3.1.3. Overriding Registration Procedures
Experience has shown that the documented IANA considerations for
individual protocols do not always adequately cover the reality of
registry operation or are not sufficiently clear. In addition,
documented IANA considerations are sometimes found to be too
stringent to allow even working group documents (for which there is
strong consensus) to perform a registration in advance of actual RFC
publication.
In order to allow assignments in such cases, the IESG can 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 takes such action, this 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 they are unable to resolve, or where registration requests or
patterns of requests appear to be unusual or abusive.
3.2. 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.
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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
registrations. Typically, the document will populate that new column
itself. However, if compiling that information at the time of
writing is impractical, the document could set a column-specific
registration procedure (such as Expert Review) that allows the
information to be assembled and provided to IANA after publication.
Other changes to the structure of an existing registry may require
similar clarity.
Registry modification requires approval from the change controller.
Modifying a registry created by an IETF stream RFC does not
automatically require an IETF stream RFC of the same type (e.g.,
Standards Track or Informational), although the change controller
could choose to require it.
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 RFC. Example documents that
updated the guidelines for assignments in pre-existing registries
include: [RFC6195], [RFC6929], and [RFC8615].
3.3. Closing, Obsoleting, and Deprecating Registries and Registrations
Sometimes IANA is asked 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.
When a registry is closed or declared obsolete, IANA will update its
registration procedure field to indicate that the registry has been
closed and list the document that closes it as an additional
reference for the registry itself, without removing any existing
reference(s). The document can also provide a note to be added to
the registry by IANA, such as if the document authors have additional
useful information about the change.
Specific entries in a registry can be marked as "obsolete" (no longer
in use) or "deprecated" (use is not recommended).
Unless instructed to do otherwise, IANA will not re-assign deprecated
or obsolete values until all other available values have been
exhausted.
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Such changes to registries and registered values are subject to
normal change controls (see Section 2.5). Any closure, obsolescence,
or deprecation serves to annotate the registry involved; the
information in the registry remains there for informational and
historic purposes.
3.4. 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.
3.5. 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 3.1.1 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.
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3.6. 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:
* 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.)
* 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.
* 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].
* It may be useful to differentiate between revocation, release, and
transfer. Revocation occurs when IANA removes an assignment in
accordance with IETF instructions (whether the source is the IESG,
a designated expert, working group chairs, or a document); 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.
3.7. 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.
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3.7.1. Organizing "bis" Considerations
When reviewing a "bis" document that obsoletes an earlier document,
IANA has two concerns: 1) identifying new actions, and 2) determining
whether existing references need to be replaced.
Some authors choose to replicate all or part of the original
document's IANA Considerations section. However, new actions edited
into existing text can be hard to identify. Documents that take this
approach should provide a subsection called "New IANA Actions." This
can be a brief list or summary, and it could include pointers to
tables or other parts of the section, if those details can't be moved
from another location. This subsection should also tell IANA how to
treat references to existing registrations, as described in
Section 3.7.3.
If the entire IANA Considerations section should be reproduced,
consider placing it in an "RFC XXXX IANA Considerations" subsection.
When deciding how much, if any, of the original document's IANA
Considerations section to include in a new IANA Considerations
section, consider what the registry user might be looking for. If
the original document included registration instructions, for
example, and the new document does not, an applicant unfamiliar with
RFC obsoletion might not guess that there were instructions to find.
If you don't want to repeat information provided in the earlier
document, the IANA Considerations section should at least point users
to the appropriate section in that document.
3.7.2. Handling Existing References
In general, 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.
If references should not be updated, consider whether IANA should
also label those registrations "obsolete" or "deprecated." IANA will
list the new document as an additional reference, but leave the
original reference in place.
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
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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.
While references to obsoleted documents are typically replaced,
references to updated documents are often left intact. However,
authors should check any references to the updated document in the
registries.
3.7.3. Describing Updates to IANA
It is extremely important to be clear in your instructions,
especially in cases where some references need to be updated and
others do not.
If the original document is being obsoleted, the IANA Considerations
must account for all references to it in the IANA registries.
However, unless those references include section numbers that need to
be updated, the new IANA Considerations section does not have to name
the individual registries and registrations that need reference
updates. For IANA, naming the affected registry groups (see
Section 2.1) and providing their URLs is sufficient (although it
could be more useful to readers to specify registries and provide
their URLs).
If all references to the original document should be updated, the
IANA Considerations can simply state that all of the references in a
list of groups (or registries) should be updated.
If any references should be left intact, the IANA Considerations
could list the groups that should have all of their references
updated, then state that in another group, all of the registrations
other than X, Y, and Z, should have their references replaced. That
text should also identify any original registrations that should be
marked as "deprecated" or "obsoleted."
Authors need to account not only for the original document's registry
actions, but for any references to the document that might have been
added to the IANA registries after it was published. These
references can appear in registries and registry groups that were not
touched by the original document. The source of these "extra"
references is typically a later RFC that registered a value, but
listed an older RFC in the reference field instead of listing itself.
IANA can supply a list of registry groups that contain references to
the original document.
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Example of an RFC that tells IANA how to update or deprecate existing
references and registrations:
The BGP Tunnel Encapsulation Attribute [RFC9012]
%% NOTE TO IANABIS: More examples may be added here. %%
4. Designated Experts and Mailing List Reviews
4.1. The Motivation for Designated Experts
Mailing list discussions can provide valuable technical input, but
they often lack clear resolution, and IANA cannot monitor all lists
or assess consensus. Therefore, IANA relies on designated experts to
evaluate requests and recommend whether assignments should be made.
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 to the expert, who provides a recommendation. Registrants
typically do not interact directly with experts unless the expert
initiates contact (with IANA in copy, if they wish for IANA to retain
records of the details of the request). Each registry lists its
designated experts.
It will often be useful to use a designated expert only some of the
time, as a supplement to other processes. For more discussion of
that topic, see Section 2.3.13.
4.2. 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 4.3. Designated experts are generally
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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 may have a single chair responsible
for defining how requests are to be assigned to and reviewed by
experts. If a registry receives a relatively high volume of
requests, IANA might assign requests to individual members in
sequential or approximate random order. More often, IANA will send
requests to the group of experts, and consider the review complete
when a certain number of replies have been received, as specified by
the group itself. 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 (typically the IESG) may need to step in to resolve the problem.
When designated experts have a conflict of interest for a particular
review (if they are, for example, authors or significant proponents
of a specification related to the registration under review), those
experts should recuse themselves. In the event that all of the
designated experts are conflicted, they should ask that a temporary
expert be designated for the conflicted review. The responsible AD
may then handle the review or appoint someone to take it.
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.
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4.2.1. 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
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.
4.3. Designated Expert Reviews
In the years since [RFC2434] was published and put to use, experience
has led to the following observations:
* Designated experts should respond promptly, typically within a
week for simple requests to a few weeks for more complex ones.
Extended delays can impact requesters, particularly when
assignments are needed to support product releases. While some
reviews may take longer, the process should begin promptly, and
both IANA and the requester should have visibility into its
progress if additional time is needed.
* If a designated expert does not respond to IANA's requests within
the period specified by the IANA agreement with the IETF
(currently 30 days), either with a response or with a reasonable
explanation for the delay (some requests may be particularly
complex), IANA must raise the issue with the IESG. Repeated
failures to respond can delay evaluations and assignments, and the
IESG should either address the issue with the expert or appoint a
new one.
* 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. If a request is rejected and the decision may be
controversial, the expert should have support from other subject
matter experts and be able to justify the decision to the
community.
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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 4.4). Reasons that have
been used to deny requests have included these:
* 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.
* Documentation is not of sufficient clarity to evaluate or ensure
interoperability.
* 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.
* The extension would cause problems with existing deployed systems.
* 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.
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4.4. 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. Unless the authors or chairs have already requested and
obtained registration, IANA will initiate reviews during IETF Last
Call. 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 primary responsibility held by the
document's Area Director, to be alert to such situations and to
recognize that such changes need to be checked.
When a registration requested by a document requires expert review,
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.
4.5. 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.
Registry experts may benefit from a registration-specific mailing
list where they can discuss requests. Lists can be set up where the
participants are just the designated experts, the experts plus
applicants, or the whole community. In general, the following should
be taken into account:
* Name a mailing list to be created by the IETF. (IANA does not
create or maintain mailing lists.) An existing IETF list can be
used, but consider whether the traffic would be problematic in
either direction (too much noise, too many requests).
* Consider whether the list should be limited to experts or open to
the public. Most expert review mailing lists are open.
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* Set a deadline by which an expert should notify IANA that a
request has been approved, barring complications. Three weeks is
a common deadline.
* Keep in mind that IANA does not monitor expert review mailing
lists. Consider whether applicants should be instructed to submit
their requests to IANA instead of the mailing list. In such
cases, IANA would forward the request to the list with the
applicant in copy. Alerting IANA to the existence of the request
at the outset means that IANA can watch for signs of inactivity
and send reminders to non-responsive expert groups.
* When a document that creates a list tells applicants to write
directly to the list instead of IANA, IANA posts a note in the
registry that directs users to the list and tells them to contact
IANA if they don't receive a response by the deadline cited in the
document. However, not all applicants will consult the registry
before submitting an application.
Examples:
CBOR Web Token (CWT) expert review mailing list [RFC8392]
TLS expert review mailing list [RFC9847]
5. 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 2.3.1.
Experimental: Available for general experimental use as described
in [RFC3692]. IANA does not record specific assignments for
any particular use.
Unassigned: Not currently assigned, and available for assignment
via documented procedures. While it's generally clear that
any values that are not registered are unassigned and
available for assignment, it is sometimes useful to
explicitly specify that situation. Note that this is
distinctly different from "Reserved".
Reserved: Not assigned and not available for assignment.
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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 IETF, as
represented by the IESG, for registries created by RFCs in
the IETF Stream).
%% QUESTION FOR IANABIS: Are the next two new paragraphs
sufficient/appropriate? %%
Reserved values may be specified further as "Reserved for
Private Use," "Reserved for Experimental Use," or "Reserved
for Future Extension". (Historically, many codepoints
reserved for future extension have not been given any
special label beyond "Reserved.")
When reserving a codepoint, consider whether deprecation or
obsoletion would be more appropriate. See [RFC3692].
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.
6. 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:
* 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.
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* 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.
* 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]".
* For documentation of a new registry, the reference should provide
information about the registry itself, not just a pointer to the
creation of it. Useful information includes the purpose of the
registry, a rationale for its creation, documentation of the
process and policy for new registrations, guidelines for new
registrants or designated experts, and other such related
information. But note that, while it's important to include this
information in the document, it needn't all be in the IANA
Considerations section. See Section 1.1.
7. 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.
8. IESG Responsibilities and Capabilities
The following describes the registry-related actions the IESG must
perform:
* Represent the IETF as change controller: Section 2.5
* Review registration requests that require direct IESG approval:
Section 2.3.10
* Designate and manage experts: Section 4
* Review IANA Considerations sections, keeping in mind that IANA
cannot determine whether a given set of registration procedures is
appropriate for a new registry. For a discussion of common
procedures, see Section 2.3.
The following describes the actions the IESG can take when needed,
along with circumstances when such intervention might be appropriate:
* Modify existing registries: Section 3.2
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* Override registration procedures: Section 3.1.3
* Advise and direct IANA as needed on topics such as unusual
requests, missing instructions, unreachable change controllers:
Section 3.1.3, Section 3.4, Section 3.5, and Section 3.6
9. Language and Formatting in the IANA Considerations Section
IANA doesn't require a specific format, but the following
recommendations might simplify the writing process and result in a
cleaner section:
Subsections:
Consider using one or more levels of subsection to group and
separate actions that affect different registry groups and
registries. Subsections can also be useful for setting off and
creating distinct references for registration templates,
instructions to designated experts, and, if necessary, brief
summaries or discussions of the action. (Note: if the document
will obsolete an earlier RFC, see Section 3.7.)
Verb Tense:
Don't use past tense to describe registry actions unless they've
already been completed. The RFC Editor can convert future tense
to past tense during the editing process.
Requests vs. Instructions:
"IANA is requested to perform action X" and "IANA will perform
action X" are both fine.
Tables:
If the content of a field will be identical for every entry in a
table, that field can be omitted from the table in favor of a
sentence that tells IANA how to populate it.
URLs:
For registry users' convenience, any registry name should be
accompanied by the URL for the registry group. For the QUIC
group, for example, the URL is https://www.iana.org/assignments/
quic.
References:
If no "Reference" field is included, IANA will list the document
itself as the reference for any registry or registration requested
in the IANA Considerations section. IANA will not specify section
numbers unless the IANA Considerations section provides them. For
information about selecting references, see Section 6.
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Numeric Values:
If the document is creating a registry, it should specify the
initial values. If the document is registering values in an
existing registry, it should refer to those values as "TBD1,"
"TBD2," etc.
While IANA is the primary audience, the section should also be clear
enough for registry users who need to find registration instructions
or confirm the source of a registration.
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. 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).
10. 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.
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.
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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.
11. IANA Considerations
This document requires that IANA update references, add columns to
registries, and repurpose an existing registry, as described below.
11.1. Reference Updates
IANA will replace references to [RFC8126] with references to this
document across the iana.org website.
11.2. Change Controller Fields
IANA will create a "Change Controller" field for all new registries
that use the "First Come First Served," "Expert Review,"
"Specification Required," or "RFC Required" registration procedure,
or any procedure that does not require an IETF-stream RFC for
registration.
In the future, IANA will add empty "Change Controller" fields to
existing registries that use those procedures but lack that field.
11.3. IESG-Recognized Standards-Related Organization Registry
IANA will make the following changes to the registry at [IESG-REG],
originally created as a list of organizations approved by the IESG
for standards-tree media type registration:
* Change the name of the registry and registry group from
"Standards-related organizations that have registered Media Types
in the Standards Tree" to "IESG-Recognized Standards-Related
Organizations"
* List this document as an additional reference for the registry,
leaving the reference to [RFC6838] in place
Existing registrations will remain in place.
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At the time of publication, registered organizations will be eligible
for any procedure that requires IESG recognition of this type. If
necessary, however, the registry could be restructured to indicate
that an organization's eligibility is restricted to specific
registries or procedures.
11.3.1. Registration Procedure
The registration procedure will continue to be listed as "IESG
Approval."
When IANA receives a registration request that cannot be processed
unless the IESG recognizes the proposed registrant as a standards-
related organization, IANA will check this repurposed registry for
the organization name. If the organization has not been registered,
IANA will submit a request for recognition to the IESG.
When the IESG formally recognizes an organization as standards-
related, IANA will add the organization to the registry.
12. Changes Relative to Earlier Editions of BCP 26
12.1. 2026: Changes in This Document Relative to RFC 8126
As of -04, this section is incomplete.
Registration procedure updates:
* Added "With Expert Review" option for registration procedures that
require RFC publication Section 2.3.11
* Specification Required changes pending (see
[I-D.nottingham-ianabis-spec-reqd])
* Added subsections to and expanded Section 2.3.13, Using Multiple
Policies
Other changes and additions:
* Added "registry group," "registry," and "subregistry" definitions
to Section 2.1
* Added Section 2.6, Registry Creation and Design Considerations
* Updated Section 3.7, What to Do in "bis" Documents
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* Required that authors refrain from requesting or suggesting
specific values in an I-D, except where a method for doing so has
been established
* Turned "Standards-related organizations that have registered Media
Types in the Standards Tree" registry [RFC6838] into a general-
purpose "IESG-Recognized Standards-Related Organizations" registry
Clarifications and such:
* Moved information about creating and updating registries into
Section 2 and Section 3, respectively.
12.2. 2016: Changes in This Document Relative to RFC 5226
Significant additions:
* Removed RFC 2119 key words, boilerplate, and reference, preferring
plain English -- this is not a protocol specification.
* Added Section 1.1, Keep IANA Considerations for IANA
* Added Section 1.2, For Updated Information
* Added Section 2.1, Organization of Registries
* Added best practice for selecting an appropriate policy into
Section 2.3.
* Added Section 2.3.13, Using Multiple Policies in Combination
* Added Section 2.5, Specifying Change Control for a Registry
* Added Section 2.6.6, Early Allocations
* Moved each well-known policy into a separate subsection of
Section 2.3.
* Added Section 4.4, Expert Reviews and the Document Lifecycle
* Added Section 6, Documentation References in IANA Registries
* Added Section 3.7, What to Do in "bis" Documents
* Added Contact Person vs Assignee or Owner
* Added Section 3.3, Closing or Obsoleting a Registry/Registrations
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Clarifications and such:
* Some reorganization -- moved text around for clarity and easier
reading.
* Made clarifications about identification of IANA registries and
use of URLs for them.
* Clarified the distinction between "Unassigned" and "Reserved".
* Made some clarifications in "Expert Review" about instructions to
the designated expert.
* Made some clarifications in "Specification Required" about how to
declare this policy.
* Assorted minor clarifications and editorial changes throughout.
12.3. 2008: Changes in RFC 5226 Relative to RFC 2434
Changes include:
* 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.
* Numerous editorial changes to improve readability.
* 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.
* Added "RFC Required" to list of defined policies.
* Much more explicit directions and examples of "what to put in
RFCs".
* "Specification Required" now implies use of a designated expert to
evaluate specs for sufficient clarity.
* Added a section describing provisional registrations.
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* 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.
* Changed wording to remove any special appeals path. The normal
RFC 2026 appeals path is used.
* Added a section about reclaiming unused values.
* Added a section on after-the-fact registrations.
* Added a section indicating that mailing lists used to evaluate
possible assignments (such as by a designated expert) are subject
to normal IETF rules.
13. References
13.1. Normative References
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, DOI 10.17487/RFC2026, October 1996,
<https://www.rfc-editor.org/info/rfc2026>.
13.2. Informative References
[BCP72] Best Current Practice 72,
<https://www.rfc-editor.org/info/bcp72>.
At the time of writing, this BCP comprises the following:
Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/info/rfc3552>.
Gont, F. and I. Arce, "Security Considerations for
Transient Numeric Identifiers Employed in Network
Protocols", BCP 72, RFC 9416, DOI 10.17487/RFC9416, July
2023, <https://www.rfc-editor.org/info/rfc9416>.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[RFC1591] Postel, J., "Domain Name System Structure and Delegation",
RFC 1591, DOI 10.17487/RFC1591, March 1994,
<https://www.rfc-editor.org/info/rfc1591>.
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[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 2434,
DOI 10.17487/RFC2434, October 1998,
<https://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,
<https://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,
<https://www.rfc-editor.org/info/rfc2939>.
[RFC3228] Fenner, B., "IANA Considerations for IPv4 Internet Group
Management Protocol (IGMP)", RFC 3228,
DOI 10.17487/RFC3228, February 2002,
<https://www.rfc-editor.org/info/rfc3228>.
[RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
IETF URN Sub-namespace for Registered Protocol
Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June
2003, <https://www.rfc-editor.org/info/rfc3553>.
[RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote
Authentication Dial In User Service)", RFC 3575,
DOI 10.17487/RFC3575, July 2003,
<https://www.rfc-editor.org/info/rfc3575>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC3692] Narten, T., "Assigning Experimental and Testing Numbers
Considered Useful", BCP 82, RFC 3692,
DOI 10.17487/RFC3692, January 2004,
<https://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,
<https://www.rfc-editor.org/info/rfc3748>.
Baber & Tanamal Expires 29 April 2027 [Page 60]
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[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864,
DOI 10.17487/RFC3864, September 2004,
<https://www.rfc-editor.org/info/rfc3864>.
[RFC3942] Volz, B., "Reclassifying Dynamic Host Configuration
Protocol version 4 (DHCPv4) Options", RFC 3942,
DOI 10.17487/RFC3942, November 2004,
<https://www.rfc-editor.org/info/rfc3942>.
[RFC4005] Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
"Diameter Network Access Server Application", RFC 4005,
DOI 10.17487/RFC4005, August 2005,
<https://www.rfc-editor.org/info/rfc4005>.
[RFC4025] Richardson, M., "A Method for Storing IPsec Keying
Material in DNS", RFC 4025, DOI 10.17487/RFC4025, March
2005, <https://www.rfc-editor.org/info/rfc4025>.
[RFC4044] McCloghrie, K., "Fibre Channel Management MIB", RFC 4044,
DOI 10.17487/RFC4044, May 2005,
<https://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,
<https://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,
<https://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,
<https://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, December 2005,
<https://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,
<https://www.rfc-editor.org/info/rfc4340>.
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[RFC4422] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple
Authentication and Security Layer (SASL)", RFC 4422,
DOI 10.17487/RFC4422, June 2006,
<https://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,
<https://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, <https://www.rfc-editor.org/info/rfc4520>.
[RFC4589] Schulzrinne, H. and H. Tschofenig, "Location Types
Registry", RFC 4589, DOI 10.17487/RFC4589, July 2006,
<https://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,
<https://www.rfc-editor.org/info/rfc4727>.
[RFC5237] Arkko, J. and S. Bradner, "IANA Allocation Guidelines for
the Protocol Field", BCP 37, RFC 5237,
DOI 10.17487/RFC5237, February 2008,
<https://www.rfc-editor.org/info/rfc5237>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://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,
<https://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,
<https://www.rfc-editor.org/info/rfc5742>.
[RFC5795] Sandlund, K., Pelletier, G., and L. Jonsson, "The RObust
Header Compression (ROHC) Framework", RFC 5795,
DOI 10.17487/RFC5795, March 2010,
<https://www.rfc-editor.org/info/rfc5795>.
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[RFC5971] Schulzrinne, H. and R. Hancock, "GIST: General Internet
Signalling Transport", RFC 5971, DOI 10.17487/RFC5971,
October 2010, <https://www.rfc-editor.org/info/rfc5971>.
[RFC6014] Hoffman, P., "Cryptographic Algorithm Identifier
Allocation for DNSSEC", RFC 6014, DOI 10.17487/RFC6014,
November 2010, <https://www.rfc-editor.org/info/rfc6014>.
[RFC6195] Eastlake 3rd, D., "Domain Name System (DNS) IANA
Considerations", RFC 6195, DOI 10.17487/RFC6195, March
2011, <https://www.rfc-editor.org/info/rfc6195>.
[RFC6230] Boulton, C., Melanchuk, T., and S. McGlashan, "Media
Control Channel Framework", RFC 6230,
DOI 10.17487/RFC6230, May 2011,
<https://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, <https://www.rfc-editor.org/info/rfc6275>.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165,
RFC 6335, DOI 10.17487/RFC6335, August 2011,
<https://www.rfc-editor.org/info/rfc6335>.
[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, <https://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,
<https://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,
<https://www.rfc-editor.org/info/rfc6838>.
[RFC6924] Leiba, B., "Registration of Second-Level URN Namespaces
under "ietf"", RFC 6924, DOI 10.17487/RFC6924, April 2013,
<https://www.rfc-editor.org/info/rfc6924>.
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[RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User
Service (RADIUS) Protocol Extensions", RFC 6929,
DOI 10.17487/RFC6929, April 2013,
<https://www.rfc-editor.org/info/rfc6929>.
[RFC6994] Touch, J., "Shared Use of Experimental TCP Options",
RFC 6994, DOI 10.17487/RFC6994, August 2013,
<https://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, <https://www.rfc-editor.org/info/rfc7120>.
[RFC7499] Perez-Mendez, A., Ed., Marin-Lopez, R., Pereniguez-Garcia,
F., Lopez-Millan, G., Lopez, D., and A. DeKok, "Support of
Fragmentation of RADIUS Packets", RFC 7499,
DOI 10.17487/RFC7499, April 2015,
<https://www.rfc-editor.org/info/rfc7499>.
[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,
<https://www.rfc-editor.org/info/rfc7564>.
[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,
<https://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,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names
(URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
<https://www.rfc-editor.org/info/rfc8141>.
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/info/rfc8392>.
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[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>.
[RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers
(URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019,
<https://www.rfc-editor.org/info/rfc8615>.
[RFC8726] Farrel, A., "How Requests for IANA Action Will Be Handled
on the Independent Stream", RFC 8726,
DOI 10.17487/RFC8726, November 2020,
<https://www.rfc-editor.org/info/rfc8726>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/info/rfc9000>.
[RFC9012] Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", RFC 9012,
DOI 10.17487/RFC9012, April 2021,
<https://www.rfc-editor.org/info/rfc9012>.
[RFC9454] Fox, M., Lindem, A., and A. Retana, "Update to OSPF
Terminology", RFC 9454, DOI 10.17487/RFC9454, August 2023,
<https://www.rfc-editor.org/info/rfc9454>.
[RFC9516] Mirsky, G., Meng, W., Ao, T., Khasnabish, B., Leung, K.,
and G. Mishra, "Active Operations, Administration, and
Maintenance (OAM) for Service Function Chaining (SFC)",
RFC 9516, DOI 10.17487/RFC9516, November 2023,
<https://www.rfc-editor.org/info/rfc9516>.
[RFC9546] Mirsky, G., Chen, M., and B. Varga, "Operations,
Administration, and Maintenance (OAM) for Deterministic
Networking (DetNet) with the MPLS Data Plane", RFC 9546,
DOI 10.17487/RFC9546, February 2024,
<https://www.rfc-editor.org/info/rfc9546>.
[RFC9594] Palombini, F. and M. Tiloca, "Key Provisioning for Group
Communication Using Authentication and Authorization for
Constrained Environments (ACE)", RFC 9594,
DOI 10.17487/RFC9594, September 2024,
<https://www.rfc-editor.org/info/rfc9594>.
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[RFC9907] Bierman, A., Boucadair, M., Ed., and Q. Wu, "Guidelines
for Authors and Reviewers of Documents Containing YANG
Data Models", BCP 216, RFC 9907, DOI 10.17487/RFC9907,
March 2026, <https://www.rfc-editor.org/info/rfc9907>.
[RFC9847] Salowey, J. and S. Turner, "IANA Registry Updates for TLS
and DTLS", RFC 9847, DOI 10.17487/RFC9847, December 2025,
<https://www.rfc-editor.org/info/rfc9847>.
[RFC9904] Hardaker, W. and W. Kumari, "DNSSEC Cryptographic
Algorithm Recommendation Update Process", RFC 9904,
DOI 10.17487/RFC9904, November 2025,
<https://www.rfc-editor.org/info/rfc9904>.
[I-D.ietf-ianabis-rfc7120bis]
Baber, A. and S. Tanamal, "Early IANA Code Point
Allocation", Work in Progress, Internet-Draft, draft-ietf-
ianabis-rfc7120bis-03, 6 July 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-ianabis-
rfc7120bis-03>.
[I-D.ietf-ianabis-early-registries]
Baber, A., "Early IANA Registry Creation", Work in
Progress, Internet-Draft, draft-ietf-ianabis-early-
registries-02, 22 July 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-ianabis-
early-registries-02>.
[I-D.nottingham-ianabis-spec-reqd]
Nottingham, M., "Specification Required Sub-Policies",
Work in Progress, Internet-Draft, draft-nottingham-
ianabis-spec-reqd-03, 17 August 2026,
<https://datatracker.ietf.org/doc/html/draft-nottingham-
ianabis-spec-reqd-03>.
[IESG-REG] IANA, "IESG-Recognized Standards-Related Organizations",
<https://www.iana.org/assignments/iesg-recognized-
organizations/>.
Appendix A. Acknowledgments
A.1. Acknowledgments for This Document (2026)
Barry Leiba, Michelle Cotton, and Thomas Narten edited the previous
edition of this document (RFC 8126). Most of the text from that
document remains in this edition.
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Thanks to Carsten Bormann, Marco Tiloca, and John Klensin for their
work in defining the "With Expert Review" and two-tiered registration
models, and to Paul Hoffman, Mark McFadden, Rich Salz, and Peter
Saint-Andre for their reviews and recommendations.
A.2. Acknowledgments for the Third Edition (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.
A.3. 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.
A.4. 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.
Authors' Addresses
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Amanda Baber (editor)
Internet Assigned Numbers Authority
PTI/ICANN
12025 Waterfront Drive
Los Angeles, 90094
United States of America
Email: amanda.baber@iana.org
Sabrina Tanamal (editor)
Internet Assigned Numbers Authority
PTI/ICANN
12025 Waterfront Drive
Los Angeles, 90094
United States of America
Email: sabrina.tanamal@iana.org
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