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Internet Engineering Task Force (IETF)                         M. CottonRequest for Comments: 8126                                           PTIBCP: 26                                                         B. LeibaObsoletes:5226                                      Huawei TechnologiesCategory: Best Current Practice                                T. NartenISSN: 2070-1721                                          IBM Corporation                                                               June 2017Guidelines for Writing an IANA Considerations Section in RFCsAbstract   Many protocols make use of points of extensibility that use constants   to identify various protocol parameters.  To ensure that the values   in these fields do not have conflicting uses and to promote   interoperability, their allocations are often coordinated by a   central record keeper.  For IETF protocols, that role is filled by   the Internet Assigned Numbers Authority (IANA).   To make assignments in a given registry prudently, guidance   describing the conditions under which new values should be assigned,   as well as when and how modifications to existing values can be made,   is needed.  This document defines a framework for the documentation   of these guidelines by specification authors, in order to assure that   the provided guidance for the IANA Considerations is clear and   addresses the various issues that are likely in the operation of a   registry.   This is the third edition of this document; it obsoletesRFC 5226.Status of This Memo   This memo documents an Internet Best Current Practice.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   BCPs is available inSection 2 of RFC 7841.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc8126.Cotton, et al.            Best Current Practice                 [Page 1]

RFC 8126           IANA Considerations Section in RFCs         June 2017Copyright Notice   Copyright (c) 2017 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (http://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Simplified BSD License text as described in Section 4.e of   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .41.1.  Keep IANA Considerations for IANA . . . . . . . . . . . .41.2.  For Updated Information . . . . . . . . . . . . . . . . .51.3.  A Quick Checklist Upfront . . . . . . . . . . . . . . . .52.  Creating and Revising Registries  . . . . . . . . . . . . . .72.1.  Organization of Registries  . . . . . . . . . . . . . . .82.2.  Documentation Requirements for Registries . . . . . . . .82.3.  Specifying Change Control for a Registry  . . . . . . . .112.4.  Revising Existing Registries  . . . . . . . . . . . . . .113.  Registering New Values in an Existing Registry  . . . . . . .123.1.  Documentation Requirements for Registrations  . . . . . .123.2.  Updating Existing Registrations . . . . . . . . . . . . .143.3.  Overriding Registration Procedures  . . . . . . . . . . .143.4.  Early Allocations . . . . . . . . . . . . . . . . . . . .154.  Choosing a Registration Policy and Well-Known Policies  . . .154.1.  Private Use . . . . . . . . . . . . . . . . . . . . . . .184.2.  Experimental Use  . . . . . . . . . . . . . . . . . . . .184.3.  Hierarchical Allocation . . . . . . . . . . . . . . . . .194.4.  First Come First Served . . . . . . . . . . . . . . . . .194.5.  Expert Review . . . . . . . . . . . . . . . . . . . . . .204.6.  Specification Required  . . . . . . . . . . . . . . . . .214.7.  RFC Required  . . . . . . . . . . . . . . . . . . . . . .224.8.  IETF Review . . . . . . . . . . . . . . . . . . . . . . .224.9.  Standards Action  . . . . . . . . . . . . . . . . . . . .234.10. IESG Approval . . . . . . . . . . . . . . . . . . . . . .234.11. Using the Well-Known Registration Policies  . . . . . . .244.12. Using Multiple Policies in Combination  . . . . . . . . .264.13. Provisional Registrations . . . . . . . . . . . . . . . .26Cotton, et al.            Best Current Practice                 [Page 2]

RFC 8126           IANA Considerations Section in RFCs         June 20175.  Designated Experts  . . . . . . . . . . . . . . . . . . . . .275.1.  The Motivation for Designated Experts . . . . . . . . . .275.2.  The Role of the Designated Expert . . . . . . . . . . . .275.2.1.  Managing Designated Experts in the IETF . . . . . . .295.3.  Designated Expert Reviews . . . . . . . . . . . . . . . .295.4.  Expert Reviews and the Document Lifecycle . . . . . . . .316.  Well-Known Registration Status Terminology  . . . . . . . . .317.  Documentation References in IANA Registries . . . . . . . . .328.  What to Do in "bis" Documents . . . . . . . . . . . . . . . .339.  Miscellaneous Issues  . . . . . . . . . . . . . . . . . . . .349.1.  When There Are No IANA Actions  . . . . . . . . . . . . .349.2.  Namespaces Lacking Documented Guidance  . . . . . . . . .359.3.  After-the-Fact Registrations  . . . . . . . . . . . . . .359.4.  Reclaiming Assigned Values  . . . . . . . . . . . . . . .359.5.  Contact Person vs Assignee or Owner . . . . . . . . . . .369.6.  Closing or Obsoleting a Registry/Registrations  . . . . .3710. Appeals . . . . . . . . . . . . . . . . . . . . . . . . . . .3711. Mailing Lists . . . . . . . . . . . . . . . . . . . . . . . .3712. Security Considerations . . . . . . . . . . . . . . . . . . .3713. IANA Considerations . . . . . . . . . . . . . . . . . . . . .3814. Changes Relative to Earlier Editions ofBCP 26  . . . . . . .3814.1.  2016: Changes in This Document Relative toRFC 5226  . .3814.2.  2008: Changes inRFC 5226 Relative toRFC 2434 . . . . .3915. References  . . . . . . . . . . . . . . . . . . . . . . . . .4015.1.  Normative References . . . . . . . . . . . . . . . . . .4015.2.  Informative References . . . . . . . . . . . . . . . . .40   Acknowledgments for This Document (2017)  . . . . . . . . . . . .46   Acknowledgments from the Second Edition (2008)  . . . . . . . . .46   Acknowledgments from the First Edition (1998) . . . . . . . . . .46   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .47Cotton, et al.            Best Current Practice                 [Page 3]

RFC 8126           IANA Considerations Section in RFCs         June 20171.  Introduction   Many protocols make use of points of extensibility that use constants   to identify various protocol parameters.  To ensure that the values   in these fields do not have conflicting uses and to promote   interoperability, their allocations are often coordinated by a   central record keeper.  The Protocol field in the IP header [RFC791]   and MIME media types [RFC6838] are two examples of such   coordinations.   The IETF selects an IANA Functions Operator (IFO) for protocol   parameters defined by the IETF.  In the contract between the IETF and   the current IFO (ICANN), that entity is referred to as the IANA   PROTOCOL PARAMETER SERVICES Operator, or IPPSO.  For consistency with   past practice, the IFO or IPPSO is referred to in this document as   "IANA" [RFC2860].   In this document, we call the range of possible values for such a   field a "namespace".  The binding or association of a specific value   with a particular purpose within a namespace is called an assignment   (or, variously: an assigned number, assigned value, code point,   protocol constant, or protocol parameter).  The act of assignment is   called a registration, and it takes place in the context of a   registry.  The terms "assignment" and "registration" are used   interchangeably throughout this document.   To make assignments in a given namespace prudently, guidance   describing the conditions under which new values should be assigned,   as well as when and how modifications to existing values can be made,   is needed.  This document defines a framework for the documentation   of these guidelines by specification authors, in order to assure that   the guidance for the IANA Considerations is clear and addresses the   various issues that are likely in the operation of a registry.   Typically, this information is recorded in a dedicated section of the   specification with the title "IANA Considerations".1.1.  Keep IANA Considerations for IANA   The purpose of having a dedicated IANA Considerations section is to   provide a single place to collect clear and concise information and   instructions for IANA.  Technical documentation should reside in   other parts of the document; the IANA Considerations should refer to   these other sections by reference only (as needed).  Using the IANA   Considerations section as primary technical documentation both hides   it from the target audience of the document and interferes with   IANA's review of the actions they need to take.Cotton, et al.            Best Current Practice                 [Page 4]

RFC 8126           IANA Considerations Section in RFCs         June 2017   An ideal IANA Considerations section clearly enumerates and specifies   each requested IANA action; includes all information IANA needs, such   as the full names of all applicable registries; and includes clear   references to elsewhere in the document for other information.   The IANA actions are normally phrased as requests for IANA (such as,   "IANA is asked to assign the value TBD1 from the Frobozz   Registry..."); the RFC Editor will change those sentences to reflect   the actions taken ("IANA has assigned the value 83 from the Frobozz   Registry...").1.2.  For Updated Information   IANA maintains a web page that includes additional clarification   information beyond what is provided here, such as minor updates and   summary guidance.  Document authors should check that page.  Any   significant updates to the best current practice will have to feed   into updates toBCP 26 (this document), which is definitive.      <https://iana.org/help/protocol-registration>1.3.  A Quick Checklist Upfront   It's useful to be familiar with this document as a whole.  But when   you return for quick reference, here are checklists for the most   common things you'll need to do and references to help with the less   common ones.   In general...   1.  Put all the information that IANA will need to know into the       "IANA Considerations" section of your document (seeSection 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       (seeSection 1.1).   3.  Note that the IESG has the authority to resolve issues with IANA       registrations.  If you have any questions or problems, you should       consult your document shepherd and/or working group chair, who       may ultimately involve an Area Director (seeSection 3.3).Cotton, et al.            Best Current Practice                 [Page 5]

RFC 8126           IANA Considerations Section in RFCs         June 2017   If you are creating a new registry...   1.  Give the registry a descriptive name and provide a brief       description of its use (seeSection 2.2).   2.  Identify any registry grouping that it should be part of (seeSection 2.1).   3.  Clearly specify what information is required in order to register       new items (seeSection 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       (seeSection 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 Sections2.3 and9.5).   6.  Select a registration policy -- or a set of policies -- to use       for future registrations (seeSection 4, and especially note       Sections4.11 and4.12).   7.  If you're using a policy that requires a designated expert       (Expert Review or Specification Required), understandSection 5       and provide review guidance to the designated expert (seeSection 5.3).   8.  If any items or ranges in your registry need to be reserved for       special use or are otherwise unavailable for assignment, seeSection 6.   If you are registering into an existing registry...   1.  Clearly identify the registry by its exact name and optionally by       its URL (seeSection 3.1).   2.  If the registry has multiple ranges from which assignments can be       made, make it clear which range is requested (seeSection 3.1).   3.  Avoid using specific values for numeric or bit assignments, and       let IANA pick a suitable value at registration time (seeSection 3.1).  This will avoid registration conflicts among       multiple documents.Cotton, et al.            Best Current Practice                 [Page 6]

RFC 8126           IANA Considerations Section in RFCs         June 2017   4.  For "reference" fields, use the document that provides the best       and most current documentation for the item being registered.       Include section numbers to make it easier for readers to locate       the relevant documentation (see Sections3.1 and7).   5.  Look up (in the registry's reference document) what information       is required for the registry and accurately provide all the       necessary information (seeSection 3.1).   6.  Look up (in the registry's reference document) any special rules       or processes there may be for the registry, such as posting to a       particular mailing list for comment, and be sure to follow the       process (seeSection 3.1).   7.  If the registration policy for the registry does not already       dictate the change control policy, make sure it's clear to IANA       what the change control policy is for the item, in case changes       to the registration need to be made later (seeSection 9.5).   If you're writing a "bis" document or otherwise making older   documents obsolete, seeSection 8.   If you need to make an early registration, such as for supporting   test implementations during document development, rather than waiting   for your document to be finished and approved, see [RFC7120].   If you need to change the format/contents or policies for an existing   registry, seeSection 2.4.   If you need to update an existing registration, seeSection 3.2.   If you need to close down a registry because it is no longer needed,   seeSection 9.6.2.  Creating and Revising Registries   Defining a registry involves describing the namespaces to be created,   listing an initial set of assignments (if applicable), and   documenting guidelines on how future assignments are to be made.   When defining a registry, consider structuring the namespace in such   a way that only top-level assignments need to be made with central   coordination, and those assignments can delegate lower-level   assignments so coordination for them can be distributed.  This   lessens the burden on IANA for dealing with assignments, and is   particularly useful in situations where distributed coordinators have   better knowledge of their portion of the namespace and are better   suited to handling those assignments.Cotton, et al.            Best Current Practice                 [Page 7]

RFC 8126           IANA Considerations Section in RFCs         June 20172.1.  Organization of Registries   All registries are anchored from the IANA "Protocol Registries" page:      <https://www.iana.org/protocols>   That page lists registries in protocol category groups, placing   related registries together and making it easier for users of the   registries to find the necessary information.  Clicking on the title   of one of the registries on the IANA Protocol Registries page will   take the reader to the details page for that registry.   Unfortunately, we have been inconsistent in how we refer to these   entities.  The group names, as they are referred to here, have been   variously called "protocol category groups", "groups", "top-level   registries", or just "registries".  The registries under them have   been called "registries" or "sub-registries".   Regardless of the terminology used, document authors should pay   attention to the registry groupings, should request that related   registries be grouped together to make related registries easier to   find, and, when creating a new registry, should check whether that   registry might best be included in an existing group.  That grouping   information should be clearly communicated to IANA in the registry   creation request.2.2.  Documentation Requirements for Registries   Documents that create a new namespace (or modify the definition of an   existing space) and that expect IANA to play a role in maintaining   that space (serving as a repository for registered values) must   provide clear instructions on details of the namespace, either in the   IANA Considerations section or referenced from it.   In particular, such instructions must include:   The name of the registry      This name will appear on the IANA web page and will be referred to      in future documents that need to allocate a value from the new      space.  The full name (and abbreviation, if appropriate) should be      provided.  It is highly desirable that the chosen name not be      easily confused with the name of another registry.      When creating a registry, the group that it is a part of must be      identified using its full name, exactly as it appears in the      Protocol Registries list.Cotton, et al.            Best Current Practice                 [Page 8]

RFC 8126           IANA Considerations Section in RFCs         June 2017      Providing a URL to precisely identify the registry helps IANA      understand the request.  Such URLs can be removed from the RFC      prior to final publication or left in the document for reference.      If you include iana.org URLs, IANA will provide corrections, if      necessary, during their review.   Required information for registrations      This tells registrants what information they have to include in      their registration requests.  Some registries require only the      requested value and a reference to a document where use of the      value is defined.  Other registries require a more detailed      registration template that describes relevant security      considerations, internationalization considerations, and other      such information.   Applicable registration policy      The policy that will apply to all future requests for      registration.  SeeSection 4.   Size, format, and syntax of registry entries      What fields to record in the registry, any technical requirements      on registry entries (valid ranges for integers, length limitations      on strings, and such), and the exact format in which registry      values should be displayed.  For numeric assignments, one should      specify whether values are to be recorded in decimal, in      hexadecimal, or in some other format.      Strings are expected to be ASCII, and it should be clearly      specified whether case matters, and whether, for example, strings      should be shown in the registry in uppercase or lowercase.      Strings that represent protocol parameters will rarely, if ever,      need to contain non-ASCII characters.  If non-ASCII characters are      really necessary, instructions should make it very clear that they      are allowed and that the non-ASCII characters should be      represented as Unicode characters using the "(U+XXXX)" convention.      Anyone creating such a registry should think carefully about this      and consider internationalization advice such as that in[RFC7564], Section 10.Cotton, et al.            Best Current Practice                 [Page 9]

RFC 8126           IANA Considerations Section in RFCs         June 2017   Initial assignments and reservations      Any initial assignments or registrations to be included.  In      addition, any ranges that are to be reserved for "Private Use",      "Reserved", "Unassigned", etc. (seeSection 6) should be      indicated.   For example, a document might specify a new registry by including:     ---------------------------------------------------------------     X. IANA Considerations     This document defines a new DHCP option, entitled "FooBar" (see     Section y), and assigns a value of TBD1 from the DHCP Option space     <https://www.iana.org/assignments/bootp-dhcp-parameters>     [RFC2132] [RFC2939]:                                    Data           Tag     Name            Length      Meaning           ----    ----            ------      -------           TBD1    FooBar          N           FooBar server     The FooBar option also defines an 8-bit FooType field, for which     IANA is to create and maintain a new registry entitled     "FooType values" used by the FooBar option.  Initial values for the     DHCP FooBar FooType registry are given below; future assignments     are to be made through Expert Review [BCP26].  Assignments consist     of a DHCP FooBar FooType name and its associated value.           Value    DHCP FooBar FooType Name   Definition           ----     ------------------------   ----------           0        Reserved           1        Frobnitz                   RFCXXXX, Section y.1           2        NitzFrob                   RFCXXXX, Section y.2           3-254    Unassigned           255      Reserved     ---------------------------------------------------------------   For examples of documents that establish registries, consult   [RFC3575], [RFC3968], and [RFC4520].   Any time IANA includes names and contact information in the public   registry, some individuals might prefer that their contact   information not be made public.  In such cases, arrangements can be   made with IANA to keep the contact information private.Cotton, et al.            Best Current Practice                [Page 10]

RFC 8126           IANA Considerations Section in RFCs         June 20172.3.  Specifying Change Control for a Registry   Registry definitions and registrations within registries often need   to be changed after they are created.  The process of making such   changes is complicated when it is unclear who is authorized to make   the changes.  For registries created by RFCs in the IETF stream,   change control for the registry lies by default with the IETF, via   the IESG.  The same is true for value registrations made in IETF-   stream RFCs.   Because registries can be created and registrations can be made   outside the IETF stream, it can sometimes be desirable to have change   control outside the IETF and IESG, and clear specification of change   control policies is always helpful.   It is advised, therefore, that all registries that are created   clearly specify a change control policy and a change controller.  It   is also advised that registries that allow registrations from outside   the IETF stream include, for each value, the designation of a change   controller for that value.  If the definition or reference for a   registered value ever needs to change, or if a registered value needs   to be deprecated, it is critical that IANA know who is authorized to   make the change.  For example, the Media Types registry [RFC6838]   includes a "Change Controller" in its registration template.  See   alsoSection 9.5.2.4.  Revising Existing Registries   Updating the registration process or making changes to the format of   an already existing (previously created) registry (whether created   explicitly or implicitly) follows a process similar to that used when   creating a new registry.  That is, a document is produced that makes   reference to the existing namespace and then provides detailed   guidance for handling assignments in the registry or detailed   instructions about the changes required.   If a change requires a new column in the registry, the instructions   need to be clear about how to populate that column for the existing   entries.  Other changes may require similar clarity.   Such documents are normally processed with the same document status   as the document that created the registry.  Under some circumstances,   such as with a straightforward change that is clearly needed (such as   adding a "status" column), or when an earlier error needs to be   corrected, the IESG may approve an update to a registry without   requiring a new document.Cotton, et al.            Best Current Practice                [Page 11]

RFC 8126           IANA Considerations Section in RFCs         June 2017   Example documents that updated the guidelines for assignments in   pre-existing registries include: [RFC6895], [RFC3228], and [RFC3575].3.  Registering New Values in an Existing Registry3.1.  Documentation Requirements for Registrations   Often, documents request an assignment in an existing registry (one   created by a previously published document).   Such documents should clearly identify the registry into which each   value is to be registered.  Use the exact registry name as listed on   the IANA web page, and cite the RFC where the registry is defined.   When referring to an existing registry, providing a URL to precisely   identify the registry is helpful (seeSection 2.2).   There is no need to mention what the assignment policy is when making   new assignments in existing registries, as that should be clear from   the references.  However, if multiple assignment policies might   apply, as in registries with different ranges that have different   policies, it is important to make it clear which range is being   requested, so that IANA will know which policy applies and can assign   a value in the correct range.   Be sure to provide all the information required for a registration,   and follow any special processes that are set out for the registry.   Registries sometimes require the completion of a registration   template for registration or ask registrants to post their request to   a particular mailing list for discussion prior to registration.  Look   up the registry's reference document: the required information and   special processes should be documented there.   Normally, numeric values to be used are chosen by IANA when the   document is approved; drafts should not specify final values.   Instead, placeholders such as "TBD1" and "TBD2" should be used   consistently throughout the document, giving each item to be   registered a different placeholder.  The IANA Considerations should   ask the RFC Editor to replace the placeholder names with the IANA-   assigned values.  When drafts need to specify numeric values for   testing or early implementations, they will either request early   allocation (seeSection 3.4) or use values that have already been set   aside for testing or experimentation (if the registry in question   allows that without explicit assignment).  It is important that   drafts not choose their own values, lest IANA assign one of those   values to another document in the meantime.  A draft can request a   specific value in the IANA Considerations section, and IANA willCotton, et al.            Best Current Practice                [Page 12]

RFC 8126           IANA Considerations Section in RFCs         June 2017   accommodate such requests when possible, but the proposed number   might have been assigned to some other use by the time the draft is   approved.   Normally, text-string values to be used are specified in the   document, as collisions are less likely with text strings.  IANA will   consult with the authors if there is, in fact, a collision, and a   different value has to be used.  When drafts need to specify string   values for testing or early implementations, they sometimes use the   expected final value.  But it is often useful to use a draft value   instead, possibly including the draft version number.  This allows   the early implementations to be distinguished from those implementing   the final version.  A document that intends to use "foobar" in the   final version might use "foobar-testing-draft-05" for the -05 version   of the draft, for example.   For some registries, there is a long-standing policy prohibiting   assignment of names or codes on a vanity or organization-name basis.   For example, codes might always be assigned sequentially unless there   is a strong reason for making an exception.  Nothing in this document   is intended to change those policies or prevent their future   application.   As an example, the following text could be used to request assignment   of a DHCPv6 option number:      IANA is asked to assign an option code value of TBD1 to the DNS      Recursive Name Server option and an option code value of TBD2 to      the Domain Search List option from the DHCP option code space      defined inSection 24.3 of RFC 3315.   The IANA Considerations section should summarize all of the IANA   actions, with pointers to the relevant sections elsewhere in the   document as appropriate.  Including section numbers is especially   useful when the reference document is large; the section numbers will   make it easier for those searching the reference document to find the   relevant information.   When multiple values are requested, it is generally helpful to   include a summary table of the additions/changes.  It is also helpful   for this table to be in the same format as it appears or will appear   on the IANA web site.  For example:     Value     Description          Reference     --------  -------------------  ---------     TBD1      Foobar               this RFC,Section 3.2     TBD2      Gumbo                this RFC,Section 3.3     TBD3      Banana               this RFC,Section 3.4Cotton, et al.            Best Current Practice                [Page 13]

RFC 8126           IANA Considerations Section in RFCs         June 2017   Note: In cases where authors feel that including the full table of   changes is too verbose or repetitive, authors should still include   the table in the draft, but may include a note asking that the table   be removed prior to publication of the final RFC.3.2.  Updating Existing Registrations   Even after a number has been assigned, some types of registrations   contain additional information that may need to be updated over time.   For example, MIME media types, character sets, and language tags   typically include more information than just the registered value   itself, and may need updates to items such as point-of-contact   information, security issues, pointers to updates, and literature   references.   In such cases, the document defining the namespace must clearly state   who is responsible for maintaining and updating a registration.   Depending on the registry, it may be appropriate to specify one or   more of:   o  Letting registrants and/or nominated change controllers update      their own registrations, subject to the same constraints and      review as with new registrations.   o  Allowing attachment of comments to the registration.  This can be      useful in cases where others have significant objections to a      registration, but the author does not agree to change the      registration.   o  Designating the IESG, a designated expert, or another entity as      having the right to change the registrant associated with a      registration and any requirements or conditions on doing so.  This      is mainly to get around the problem when a registrant cannot be      reached in order to make necessary updates.3.3.  Overriding Registration Procedures   Experience has shown that the documented IANA considerations for   individual protocols do not always adequately cover the reality of   registry operation or are not sufficiently clear.  In addition,   documented IANA considerations are sometimes found to be too   stringent to allow even working group documents (for which there is   strong consensus) to perform a registration in advance of actual RFC   publication.Cotton, et al.            Best Current Practice                [Page 14]

RFC 8126           IANA Considerations Section in RFCs         June 2017   In order to allow assignments in such cases, the IESG is granted   authority to override registration procedures and approve assignments   on a case-by-case basis.   The intention here is not to overrule properly documented procedures   or to obviate the need for protocols to properly document their IANA   considerations.  Rather, it is to permit assignments in specific   cases where it is obvious that the assignment should just be made,   but updating the IANA process beforehand is too onerous.   When the IESG is required to take action as described above, it is a   strong indicator that the applicable registration procedures should   be updated, possibly in parallel with the work that instigated it.   IANA always has the discretion to ask the IESG for advice or   intervention when they feel it is needed, such as in cases where   policies or procedures are unclear to them, where they encounter   issues or questions they are unable to resolve, or where registration   requests or patterns of requests appear to be unusual or abusive.3.4.  Early Allocations   IANA normally takes its actions when a document is approved for   publication.  There are times, though, when early allocation of a   value is important for the development of a technology, for example,   when early implementations are created while the document is still   under development.   IANA has a mechanism for handling such early allocations in some   cases.  See [RFC7120] for details.  It is usually not necessary to   explicitly mark a registry as allowing early allocation, because the   general rules will apply.4.  Choosing a Registration Policy and Well-Known Policies   A registration policy is the policy that controls how new assignments   in a registry are accepted.  There are several issues to consider   when defining the registration policy.   If the registry's namespace is limited, assignments will need to be   made carefully to prevent exhaustion.Cotton, et al.            Best Current Practice                [Page 15]

RFC 8126           IANA Considerations Section in RFCs         June 2017   Even when the space is essentially unlimited, it is still often   desirable to have at least a minimal review prior to assignment in   order to:   o  prevent the hoarding of or unnecessary wasting of values.  For      example, if the space consists of text strings, it may be      desirable to prevent entities from obtaining large sets of strings      that correspond to desirable names (existing company names, for      example).   o  provide a sanity check that the request actually makes sense and      is necessary.  Experience has shown that some level of minimal      review from a subject matter expert is useful to prevent      assignments in cases where the request is malformed or not      actually needed (for example, an existing assignment for an      essentially equivalent service already exists).   Perhaps most importantly, unreviewed extensions can impact   interoperability and security.  See [RFC6709].   When the namespace is essentially unlimited and there are no   potential interoperability or security issues, assigned numbers can   usually be given out to anyone without any subjective review.  In   such cases, IANA can make assignments directly, provided that IANA is   given detailed instructions on what types of requests it should   grant, and it is able to do so without exercising subjective   judgment.   When this is not the case, some level of review is required.   However, it's important to balance adequate review and ease of   registration.  In many cases, those making registrations will not be   IETF participants; requests often come from other standards   organizations, from organizations not directly involved in standards,   from ad-hoc community work (from an open-source project, for   example), and so on.  Registration must not be unnecessarily   difficult, unnecessarily costly (in terms of time and other   resources), nor unnecessarily subject to denial.   While it is sometimes necessary to restrict what gets registered   (e.g., for limited resources such as bits in a byte, or for items for   which unsupported values can be damaging to protocol operation), in   many cases having what's in use represented in the registry is more   important.  Overly strict review criteria and excessive cost (in time   and effort) discourage people from even attempting to make a   registration.  If a registry fails to reflect the protocol elements   actually in use, it can adversely affect deployment of protocols on   the Internet, and the registry itself is devalued.Cotton, et al.            Best Current Practice                [Page 16]

RFC 8126           IANA Considerations Section in RFCs         June 2017   Therefore, it is important to think specifically about the   registration policy, and not just pick one arbitrarily nor copy text   from another document.  Working groups and other document developers   should use care in selecting appropriate registration policies when   their documents create registries.  They should select the least   strict policy that suits a registry's needs, and look for specific   justification for policies that require significant community   involvement (those stricter than Expert Review or Specification   Required, in terms of the well-known policies).  The needs here will   vary from registry to registry, and, indeed, over time, and this BCP   will not be the last word on the subject.   The following policies are defined for common usage.  These cover a   range of typical policies that have been used to describe the   procedures for assigning new values in a namespace.  It is not   strictly required that documents use these terms; the actual   requirement is that the instructions to IANA be clear and   unambiguous.  However, use of these terms is strongly recommended   because their meanings are widely understood.  Newly minted policies,   including ones that combine the elements of procedures associated   with these terms in novel ways, may be used if none of these policies   are suitable; it will help the review process if an explanation is   included as to why that is the case.  The terms are fully explained   in the following subsections.      1.   Private Use      2.   Experimental Use      3.   Hierarchical Allocation      4.   First Come First Served      5.   Expert Review      6.   Specification Required      7.   RFC Required      8.   IETF Review      9.   Standards Action      10.  IESG Approval   It should be noted that it often makes sense to partition a namespace   into multiple categories, with assignments within each category   handled differently.  Many protocols now partition namespaces into   two or more parts, with one range reserved for Private or   Experimental Use while other ranges are reserved for globally unique   assignments assigned following some review process.  Dividing a   namespace into ranges makes it possible to have different policies in   place for different ranges and different use cases.   Similarly, it will often be useful to specify multiple policies in   parallel, with each policy being used under different circumstances.   For more discussion of that topic, seeSection 4.12.Cotton, et al.            Best Current Practice                [Page 17]

RFC 8126           IANA Considerations Section in RFCs         June 2017   Examples of RFCs that specify multiple policies in parallel:      LDAP [RFC4520]      TLS ClientCertificateType Identifiers [RFC5246] (as detailed in      the subsections below)      MPLS Pseudowire Types Registry [RFC4446]4.1.  Private Use   Private Use is for private or local use only, with the type and   purpose defined by the local site.  No attempt is made to prevent   multiple sites from using the same value in different (and   incompatible) ways.  IANA does not record assignments from registries   or ranges with this policy (and therefore there is no need for IANA   to review them) and assignments are not generally useful for broad   interoperability.  It is the responsibility of the sites making use   of the Private Use range to ensure that no conflicts occur (within   the intended scope of use).   Examples:      Site-specific options in DHCP [RFC2939]      Fibre Channel Port Type Registry [RFC4044]      TLS ClientCertificateType Identifiers 224-255 [RFC5246]4.2.  Experimental Use   Experimental Use is similar to Private Use, but with the purpose   being to facilitate experimentation.  See [RFC3692] for details.   IANA does not record assignments from registries or ranges with this   policy (and therefore there is no need for IANA to review them) and   assignments are not generally useful for broad interoperability.   Unless the registry explicitly allows it, it is not appropriate for   documents to select explicit values from registries or ranges with   this policy.  Specific experiments will select a value to use during   the experiment.   When code points are set aside for Experimental Use, it's important   to make clear any expected restrictions on experimental scope.  For   example, say whether it's acceptable to run experiments using those   code points over the open Internet or whether such experiments should   be confined to more closed environments.  See [RFC6994] for an   example of such considerations.   Example:      Experimental Values in IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP      Headers [RFC4727]Cotton, et al.            Best Current Practice                [Page 18]

RFC 8126           IANA Considerations Section in RFCs         June 20174.3.  Hierarchical Allocation   With Hierarchical Allocation, delegated administrators are given   control over part of the namespace and can assign values in that part   of the namespace.  IANA makes allocations in the higher levels of the   namespace according to one of the other policies.   Examples:   o  DNS names - IANA manages the top-level domains (TLDs), and, as      [RFC1591] says:         Under each TLD may be created a hierarchy of names.  Generally,         under the generic TLDs the structure is very flat.  That is,         many organizations are registered directly under the TLD, and         any further structure is up to the individual organizations.   o  Object Identifiers - defined by ITU-T recommendation X.208.      According to <http://www.alvestrand.no/objectid/>, some registries      include      *  IANA, which hands out OIDs under the "Private Enterprises"         branch,      *  ANSI, which hands out OIDs under the "US Organizations" branch,         and      *  BSI, which hands out OIDs under the "UK Organizations" branch.   o  URN namespaces - IANA registers URN Namespace IDs (NIDs      [RFC8141]), and the organization registering an NID is responsible      for allocations of URNs within that namespace.4.4.  First Come First Served   For the First Come First Served policy, assignments are made to   anyone on a first come, first served basis.  There is no substantive   review of the request, other than to ensure that it is well-formed   and doesn't duplicate an existing assignment.  However, requests must   include a minimal amount of clerical information, such as a point of   contact (including an email address, and sometimes a postal address)   and a brief description of how the value will be used.  Additional   information specific to the type of value requested may also need to   be provided, as defined by the namespace.  For numbers, IANA   generally assigns the next in-sequence unallocated value, but other   values may be requested and assigned if an extenuating circumstance   exists.  With names, specific text strings can usually be requested.Cotton, et al.            Best Current Practice                [Page 19]

RFC 8126           IANA Considerations Section in RFCs         June 2017   When creating a new registry with First Come First Served as the   registration policy, in addition to the contact person field or   reference, the registry should contain a field for change controller.   Having a change controller for each entry for these types of   registrations makes authorization of future modifications more clear.   SeeSection 2.3.   It is important that changes to the registration of a First Come   First Served code point retain compatibility with the current usage   of that code point, so changes need to be made with care.  The change   controller should not, in most cases, be requesting incompatible   changes nor repurposing a registered code point.  See also Sections   9.4 and 9.5.   A working group or any other entity that is developing a protocol   based on a First Come First Served code point has to be extremely   careful that the protocol retains wire compatibility with current use   of the code point.  Once that is no longer true, the new work needs   to change to a different code point (and register that use at the   appropriate time).   It is also important to understand that First Come First Served   really has no filtering.  Essentially, any well-formed request is   accepted.   Examples:      SASL mechanism names [RFC4422]      LDAP Protocol Mechanisms and LDAP Syntax [RFC4520]4.5.  Expert Review   For the Expert Review policy, review and approval by a designated   expert (seeSection 5) is required.  While this does not necessarily   require formal documentation, information needs to be provided with   the request for the designated expert to evaluate.  The registry's   definition needs to make clear to registrants what information is   necessary.  The actual process for requesting registrations is   administered by IANA (seeSection 1.2 for details).   (This policy was also called "Designated Expert" in earlier editions   of this document.  The current term is "Expert Review".)   The required documentation and review criteria, giving clear guidance   to the designated expert, should be provided when defining the   registry.  It is particularly important to lay out what should be   considered when performing an evaluation and reasons for rejecting a   request.  It is also a good idea to include, when possible, a senseCotton, et al.            Best Current Practice                [Page 20]

RFC 8126           IANA Considerations Section in RFCs         June 2017   of whether many registrations are expected over time, or if the   registry is expected to be updated infrequently or in exceptional   circumstances only.   Thorough understanding ofSection 5 is important when deciding on an   Expert Review policy and designing the guidance to the designated   expert.   Good examples of guidance to designated experts:      Extensible Authentication Protocol (EAP) [RFC3748], Sections6 and      7.2      North-Bound Distribution of Link-State and TE Information Using      BGP[RFC7752], Section 5.1   When creating a new registry with Expert Review as the registration   policy, in addition to the contact person field or reference, the   registry should contain a field for change controller.  Having a   change controller for each entry for these types of registrations   makes authorization of future modifications more clear.  SeeSection 2.3.   Examples:      EAP Method Types [RFC3748]      HTTP Digest AKA algorithm versions [RFC4169]      URI schemes [RFC7595]      GEOPRIV Location Types [RFC4589]4.6.  Specification Required   For the Specification Required policy, review and approval by a   designated expert (seeSection 5) is required, and the values and   their meanings must be documented in a permanent and readily   available public specification, in sufficient detail so that   interoperability between independent implementations is possible.   This policy is the same as Expert Review, with the additional   requirement of a formal public specification.  In addition to the   normal review of such a request, the designated expert will review   the public specification and evaluate whether it is sufficiently   stable and permanent, and sufficiently clear and technically sound to   allow interoperable implementations.   The intention behind "permanent and readily available" is that a   document can reasonably be expected to be findable and retrievable   long after IANA assignment of the requested value.  Publication of an   RFC is an ideal means of achieving this requirement, but   Specification Required is intended to also cover the case of aCotton, et al.            Best Current Practice                [Page 21]

RFC 8126           IANA Considerations Section in RFCs         June 2017   document published outside of the RFC path, including informal   documentation.   For RFC publication, formal review by the designated expert is still   requested, but the normal RFC review process is expected to provide   the necessary review for interoperability.  The designated expert's   review is still important, but it's equally important to note that   when there is IETF consensus, the expert can sometimes be "in the   rough" (see also the last paragraph ofSection 5.4).   As with Expert Review (Section 4.5), clear guidance to the designated   expert should be provided when defining the registry, and thorough   understanding ofSection 5 is important.   When specifying this policy, just use the term "Specification   Required".  Some specifications have chosen to refer to it as "Expert   Review with Specification Required", and that only causes confusion.   Examples:      Diffserv-aware TE Bandwidth Constraints Model Identifiers      [RFC4124]      TLS ClientCertificateType Identifiers 64-223 [RFC5246]      ROHC Profile Identifiers [RFC5795]4.7.  RFC Required   With the RFC Required policy, the registration request, along with   associated documentation, must be published in an RFC.  The RFC need   not be in the IETF stream, but may be in any RFC stream (currently an   RFC may be in the IETF, IRTF, IAB, or Independent Submission streams   [RFC5742]).   Unless otherwise specified, any type of RFC is sufficient (currently   Standards Track, BCP, Informational, Experimental, or Historic).   Examples:      DNSSEC DNS Security Algorithm Numbers [RFC6014]      Media Control Channel Framework registries [RFC6230]      DANE TLSA Certificate Usages [RFC6698]4.8.  IETF Review   (Formerly called "IETF Consensus" in the first edition of this   document.)  With the IETF Review policy, new values are assigned only   through RFCs in the IETF Stream -- those that have been shepherded   through the IESG as AD-Sponsored or IETF working group documentsCotton, et al.            Best Current Practice                [Page 22]

RFC 8126           IANA Considerations Section in RFCs         June 2017   [RFC2026] [RFC5378], have gone through IETF Last Call, and have been   approved by the IESG as having IETF consensus.   The intent is that the document and proposed assignment will be   reviewed by the IETF community (including appropriate IETF working   groups, directorates, and other experts) and by the IESG, to ensure   that the proposed assignment will not negatively affect   interoperability or otherwise extend IETF protocols in an   inappropriate or damaging manner.   Unless otherwise specified, any type of RFC is sufficient (currently   Standards Track, BCP, Informational, Experimental, or Historic).   Examples:      IPSECKEY Algorithm Types [RFC4025]      TLS Extension Types [RFC5246]4.9.  Standards Action   For the Standards Action policy, values are assigned only through   Standards Track or Best Current Practice RFCs in the IETF Stream.   Examples:      BGP message types [RFC4271]      Mobile Node Identifier option types [RFC4283]      TLS ClientCertificateType Identifiers 0-63 [RFC5246]      DCCP Packet Types [RFC4340]4.10.  IESG Approval   New assignments may be approved by the IESG.  Although there is no   requirement that the request be documented in an RFC, the IESG has   the discretion to request documents or other supporting materials on   a case-by-case basis.   IESG Approval is not intended to be used often or as a "common case";   indeed, it has seldom been used in practice.  Rather, it is intended   to be available in conjunction with other policies as a fall-back   mechanism in the case where one of the other allowable approval   mechanisms cannot be employed in a timely fashion or for some other   compelling reason.  IESG Approval is not intended to circumvent the   public review processes implied by other policies that could have   been employed for a particular assignment.  IESG Approval would be   appropriate, however, in cases where expediency is desired and there   is strong consensus (such as from a working group) for making the   assignment.Cotton, et al.            Best Current Practice                [Page 23]

RFC 8126           IANA Considerations Section in RFCs         June 2017   Before approving a request, the IESG might consider consulting the   community, via a "call for comments" that provides as much   information as is reasonably possible about the request.   Examples:      IPv4 Multicast address assignments [RFC5771]      IPv4 IGMP Type and Code values [RFC3228]      Mobile IPv6 Mobility Header Type and Option values [RFC6275]4.11.  Using the Well-Known Registration Policies   Because the well-known policies benefit from both community   experience and wide understanding, their use is encouraged, and the   creation of new policies needs to be accompanied by reasonable   justification.   It is also acceptable to cite one or more well-known policies and   include additional guidelines for what kind of considerations should   be taken into account by the review process.   For example, for media-type registrations [RFC6838], a number of   different situations are covered that involve the use of IETF Review   and Specification Required, while also including specific additional   criteria the designated expert should follow.  This is not meant to   represent a registration procedure, but to show an example of what   can be done when special circumstances need to be covered.   The well-known policies from "First Come First Served" to "Standards   Action" specify a range of policies in increasing order of strictness   (using the numbering from the full list inSection 4):   4. First Come First Served      No review, minimal documentation.   5 and 6  (of equal strictness).      5. Expert Review         Expert review with sufficient documentation for review.      6. Specification Required         Significant stable public documentation sufficient for         interoperability.   7. RFC Required      Any RFC publication, IETF or a non-IETF Stream.   8. IETF ReviewCotton, et al.            Best Current Practice                [Page 24]

RFC 8126           IANA Considerations Section in RFCs         June 2017      RFC publication, IETF Stream only, but need not be Standards      Track.   9. Standards Action      RFC publication, IETF Stream, Standards Track or BCP only.   Examples of situations that might merit IETF Review or Standards   Action include the following:   o  When a resource is limited, such as bits in a byte (or in two      bytes, or four), or numbers in a limited range.  In these cases,      allowing registrations that haven't been carefully reviewed and      agreed to by community consensus could too quickly deplete the      allowable values.   o  When thorough community review is necessary to avoid extending or      modifying the protocol in ways that could be damaging.  One      example is in defining new command codes, as opposed to options      that use existing command codes: the former might require a strict      policy, where a more relaxed policy could be adequate for the      latter.  Another example is in defining protocol elements that      change the semantics of existing operations.   o  When there are security implications with respect to the resource,      and thorough review is needed to ensure that the new usage is      sound.  Examples of this include lists of acceptable hashing and      cryptographic algorithms, and assignment of transport ports in the      system range.   When reviewing a document that asks IANA to create a new registry or   change a registration policy to any policy more stringent than Expert   Review or Specification Required, the IESG should ask for   justification to ensure that more relaxed policies have been   considered and that the more strict policy is the right one.   Accordingly, document developers need to anticipate this and document   their considerations for selecting the specified policy (ideally, in   the document itself; failing that, in the shepherd writeup).   Likewise, the document shepherd should ensure that the selected   policies have been justified before sending the document to the IESG.   When specifications are revised, registration policies should be   reviewed in light of experience since the policies were set.4.12.  Using Multiple Policies in Combination   In some situations, it is necessary to define multiple registration   policies.  For example, registrations through the normal IETF processCotton, et al.            Best Current Practice                [Page 25]

RFC 8126           IANA Considerations Section in RFCs         June 2017   might use one policy, while registrations from outside the process   would have a different policy applied.   Thus, a particular registry might want to use a policy such as "RFC   Required" or "IETF Review" sometimes, with a designated expert   checking a "Specification Required" policy at other times.   The alternative to using a combination requires either that all   requests come through RFCs or that requests in RFCs go through review   by the designated expert, even though they already have IETF review   and consensus.   This can be documented in the IANA Considerations section when the   registry is created, for example:      IANA is asked to create the registry "Fruit Access Flags" under      the "Fruit Parameters" group.  New registrations will be permitted      through either the IETF Review policy or the Specification      Required policy [BCP26].  The latter should be used only for      registrations requested by SDOs outside the IETF.  Registrations      requested in IETF documents will be subject to IETF review.   Such combinations will commonly use one of {Standards Action, IETF   Review, RFC Required} in combination with one of {Specification   Required, Expert Review}.  Guidance should be provided about when   each policy is appropriate, as in the example above.4.13.  Provisional Registrations   Some existing registries have policies that allow provisional   registration: see URI Schemes [RFC7595] and Email Header Fields   [RFC3864].  Registrations that are designated as provisional are   usually defined as being more readily created, changed, reassigned,   moved to another status, or removed entirely.  URI Schemes, for   example, allow provisional registrations to be made with incomplete   information.   Allowing provisional registration ensures that the primary goal of   maintaining a registry -- avoiding collisions between incompatible   semantics -- is achieved without the side effect of "endorsing" the   protocol mechanism the provisional value is used for.  Provisional   registrations for codepoints that are ultimately standardized can be   promoted to permanent status.  The criteria that are defined for   converting a provisional registration to permanent will likely be   more strict than those that allowed the provisional registration.   If your registry does not have a practical limit on codepoints,   perhaps adding the option for provisional registrations might beCotton, et al.            Best Current Practice                [Page 26]

RFC 8126           IANA Considerations Section in RFCs         June 2017   right for that registry as well.5.  Designated Experts5.1.  The Motivation for Designated Experts   Discussion on a mailing list can provide valuable technical feedback,   but opinions often vary and discussions may continue for some time   without clear resolution.  In addition, IANA cannot participate in   all of these mailing lists and cannot determine if or when such   discussions reach consensus.  Therefore, IANA relies on a "designated   expert" for advice regarding the specific question of whether an   assignment should be made.  The designated expert is an individual   who is responsible for carrying out an appropriate evaluation and   returning a recommendation to IANA.   It should be noted that a key motivation for having designated   experts is for the IETF to provide IANA with a subject matter expert   to whom the evaluation process can be delegated.  IANA forwards   requests for an assignment to the expert for evaluation, and the   expert (after performing the evaluation) informs IANA as to whether   or not to make the assignment or registration.  In most cases, the   registrants do not work directly with the designated experts.  The   list of designated experts for a registry is listed in the registry.   It will often be useful to use a designated expert only some of the   time, as a supplement to other processes.  For more discussion of   that topic, seeSection 4.12.5.2.  The Role of the Designated Expert   The designated expert is responsible for coordinating the appropriate   review of an assignment request.  The review may be wide or narrow,   depending on the situation and the judgment of the designated expert.   This may involve consultation with a set of technology experts,   discussion on a public mailing list, consultation with a working   group (or its mailing list if the working group has disbanded), etc.   Ideally, the designated expert follows specific review criteria as   documented with the protocol that creates or uses the namespace.  See   the IANA Considerations sections of [RFC3748] and [RFC3575] for   specific examples.   Designated experts are expected to be able to defend their decisions   to the IETF community, and the evaluation process is not intended to   be secretive or bestow unquestioned power on the expert.  Experts are   expected to apply applicable documented review or vetting procedures,   or in the absence of documented criteria, follow generally accepted   norms such as those inSection 5.3.  Designated experts are generallyCotton, et al.            Best Current Practice                [Page 27]

RFC 8126           IANA Considerations Section in RFCs         June 2017   not expected to be "gatekeepers", setting out to make registrations   difficult to obtain, unless the guidance in the defining document   specifies that they should act as such.  Absent stronger guidance,   the experts should be evaluating registration requests for   completeness, interoperability, and conflicts with existing protocols   and options.   It has proven useful to have multiple designated experts for some   registries.  Sometimes those experts work together in evaluating a   request, while in other cases additional experts serve as backups,   acting only when the primary expert is unavailable.  In registries   with a pool of experts, the pool often has a single chair responsible   for defining how requests are to be assigned to and reviewed by   experts.  In other cases, IANA might assign requests to individual   members in sequential or approximate random order.  The document   defining the registry can, if it's appropriate for the situation,   specify how the group should work -- for example, it might be   appropriate to specify rough consensus on a mailing list, within a   related working group or among a pool of designated experts.   In cases of disagreement among multiple experts, it is the   responsibility of those experts to make a single clear recommendation   to IANA.  It is not appropriate for IANA to resolve disputes among   experts.  In extreme situations, such as deadlock, the designating   body may need to step in to resolve the problem.   If a designated expert has a conflict of interest for a particular   review (is, for example, an author or significant proponent of a   specification related to the registration under review), that expert   should recuse himself.  In the event that all the designated experts   are conflicted, they should ask that a temporary expert be designated   for the conflicted review.  The responsible AD may then appoint   someone or the AD may handle the review.   This document defines the designated expert mechanism with respect to   documents in the IETF stream only.  If other streams want to use   registration policies that require designated experts, it is up to   those streams (or those documents) to specify how those designated   experts are appointed and managed.  What is described below, with   management by the IESG, is only appropriate for the IETF stream.5.2.1.  Managing Designated Experts in the IETF   Designated experts for registries created by the IETF are appointed   by the IESG, normally upon recommendation by the relevant Area   Director.  They may be appointed at the time a document creating or   updating a namespace is approved by the IESG, or subsequently, when   the first registration request is received.  Because expertsCotton, et al.            Best Current Practice                [Page 28]

RFC 8126           IANA Considerations Section in RFCs         June 2017   originally appointed may later become unavailable, the IESG will   appoint replacements as necessary.  The IESG may remove any   designated expert that it appointed, at its discretion.   The normal appeals process, as described in[RFC2026], Section 6.5.1,   applies to issues that arise with the designated expert team.  For   this purpose, the designated expert team takes the place of the   working group in that description.5.3.  Designated Expert Reviews   In the years since [RFC2434] was published and put to use, experience   has led to the following observations:   o  A designated expert must respond in a timely fashion, normally      within a week for simple requests to a few weeks for more complex      ones.  Unreasonable delays can cause significant problems for      those needing assignments, such as when products need code points      to ship.  This is not to say that all reviews can be completed      under a firm deadline, but they must be started, and the requester      and IANA should have some transparency into the process if an      answer cannot be given quickly.   o  If a designated expert does not respond to IANA's requests within      a reasonable period of time, either with a response or with a      reasonable explanation for the delay (some requests may be      particularly complex), and if this is a recurring event, IANA must      raise the issue with the IESG.  Because of the problems caused by      delayed evaluations and assignments, the IESG should take      appropriate actions to ensure that the expert understands and      accepts his or her responsibilities, or appoint a new expert.   o  The designated expert is not required to personally bear the      burden of evaluating and deciding all requests, but acts as a      shepherd for the request, enlisting the help of others as      appropriate.  In the case that a request is denied, and rejecting      the request is likely to be controversial, the expert should have      the support of other subject matter experts.  That is, the expert      must be able to defend a decision to the community as a whole.   When a designated expert is used, the documentation should give clear   guidance to the designated expert, laying out criteria for performing   an evaluation and reasons for rejecting a request.  In the case where   there are no specific documented criteria, the presumption should be   that a code point should be granted unless there is a compelling   reason to the contrary (and see alsoSection 5.4).  Reasons that have   been used to deny requests have included these:Cotton, et al.            Best Current Practice                [Page 29]

RFC 8126           IANA Considerations Section in RFCs         June 2017   o  Scarcity of code points, where the finite remaining code points      should be prudently managed, or where a request for a large number      of code points is made and a single code point is the norm.   o  Documentation is not of sufficient clarity to evaluate or ensure      interoperability.   o  The code point is needed for a protocol extension, but the      extension is not consistent with the documented (or generally      understood) architecture of the base protocol being extended and      would be harmful to the protocol if widely deployed.  It is not      the intent that "inconsistencies" refer to minor differences "of a      personal preference nature".  Instead, they refer to significant      differences such as inconsistencies with the underlying security      model, implying a change to the semantics of an existing message      type or operation, requiring unwarranted changes in deployed      systems (compared with alternate ways of achieving a similar      result), etc.   o  The extension would cause problems with existing deployed systems.   o  The extension would conflict with one under active development by      the IETF, and having both would harm rather than foster      interoperability.   Documents must not name the designated expert(s) in the document   itself; instead, any suggested names should be relayed to the   appropriate Area Director at the time the document is sent to the   IESG for approval.  This is usually done in the document shepherd   writeup.   If the request should also be reviewed on a specific public mailing   list, its address should be specified.Cotton, et al.            Best Current Practice                [Page 30]

RFC 8126           IANA Considerations Section in RFCs         June 20175.4.  Expert Reviews and the Document Lifecycle   Review by the designated expert is necessarily done at a particular   point in time and represents review of a particular version of the   document.  While reviews are generally done around the time of IETF   Last Call, deciding when the review should take place is a question   of good judgment.  And while rereviews might be done when it's   acknowledged that the documentation of the registered item has   changed substantially, making sure that rereview happens requires   attention and care.   It is possible, through carelessness, accident, inattentiveness, or   even willful disregard, that changes might be made after the   designated expert's review and approval that would, if the document   were rereviewed, cause the expert not to approve the registration.   It is up to the IESG, with the token held by the responsible Area   Director, to be alert to such situations and to recognize that such   changes need to be checked.   For registrations made from documents on the Standards Track, there   is often expert review required (by the registration policy) in   addition to IETF consensus (for approval as a Standards Track RFC).   In such cases, the review by the designated expert needs to be   timely, submitted before the IESG evaluates the document.  The IESG   should generally not hold the document up waiting for a late review.   It is also not intended for the expert review to override IETF   consensus: the IESG should consider the review in its own evaluation,   as it would do for other Last Call reviews.6.  Well-Known Registration Status Terminology   The following labels describe the status of an assignment or range of   assignments:      Private Use:  Private use only (not assigned), as described inSection 4.1.      Experimental:  Available for general experimental use as described            in [RFC3692].  IANA does not record specific assignments for            any particular use.      Unassigned:  Not currently assigned, and available for assignment            via documented procedures.  While it's generally clear that            any values that are not registered are unassigned and            available for assignment, it is sometimes useful to            explicitly specify that situation.  Note that this is            distinctly different from "Reserved".Cotton, et al.            Best Current Practice                [Page 31]

RFC 8126           IANA Considerations Section in RFCs         June 2017      Reserved:  Not assigned and not available for assignment.            Reserved values are held for special uses, such as to extend            the namespace when it becomes exhausted.  "Reserved" is also            sometimes used to designate values that had been assigned            but are no longer in use, keeping them set aside as long as            other unassigned values are available.  Note that this is            distinctly different from "Unassigned".            Reserved values can be released for assignment by the change            controller for the registry (this is often the IESG, for            registries created by RFCs in the IETF stream).      Known Unregistered Use:  It's known that the assignment or range            is in use without having been defined in accordance with            reasonable practice.  Documentation for use of the            assignment or range may be unavailable, inadequate, or            conflicting.  This is a warning against use, as well as an            alert to network operators who might see these values in use            on their networks.7.  Documentation References in IANA Registries   Usually, registries and registry entries include references to   documentation (RFCs or other documents).  The purpose of these   references is to provide pointers for implementors to find details   necessary for implementation, NOT to simply note what document   created the registry or entry.  Therefore:   o  If a document registers an item that is defined and explained      elsewhere, the registered reference should be to the document      containing the definition, not to the document that is merely      performing the registration.   o  If the registered item is defined and explained in the current      document, it is important to include sufficient information to      enable implementors to understand the item and to create a proper      implementation.   o  If the registered item is explained primarily in a specific      section of the reference document, it is useful to include a      section reference.  For example, "[RFC4637], Section 3.2", rather      than just "[RFC4637]".   o  For documentation of a new registry, the reference should provide      information about the registry itself, not just a pointer to the      creation of it.  Useful information includes the purpose of the      registry, a rationale for its creation, documentation of the      process and policy for new registrations, guidelines for newCotton, et al.            Best Current Practice                [Page 32]

RFC 8126           IANA Considerations Section in RFCs         June 2017      registrants or designated experts, and other such related      information.  But note that, while it's important to include this      information in the document, it needn't all be in the IANA      Considerations section.  SeeSection 1.1.8.  What to Do in "bis" Documents   On occasion, an RFC is issued that obsoletes a previous edition of   the same document.  We sometimes call these "bis" documents, such as   whenRFC 4637 is to be obsoleted bydraft-ietf-foo-rfc4637bis.  When   the original document created registries and/or registered entries,   there is a question of how to handle the IANA Considerations section   in the "bis" document.   If the registrations specify the original document as a reference,   those registrations should be updated to point to the current (not   obsolete) documentation for those items.  Usually, that will mean   changing the reference to be the "bis" document.   There will, though, be times when a document updates another, but   does not make it obsolete, and the definitive reference is changed   for some items but not for others.  Be sure that the references   always point to the correct, current documentation for each item.   For example, supposeRFC 4637 registered the "BANANA" flag in the   "Fruit Access Flags" registry, and the documentation for that flag is   inSection 3.2.   The current registry might look, in part, like this:      Name      Description          Reference      --------  -------------------  ---------      BANANA    Flag for bananas[RFC4637], Section 3.2   Ifdraft-ietf-foo-rfc4637bis obsoletesRFC 4637 and, because of some   rearrangement, now documents the flag inSection 4.1.2, the IANA   Considerations of the bis document might contain text such as this:      IANA is asked to change the registration information for the      BANANA flag in the "Fruit Access Flags" registry to the      following:      Name      Description          Reference      --------  -------------------  ---------      BANANA    Flag for bananas     [[this RFC]],Section 4.2.1Cotton, et al.            Best Current Practice                [Page 33]

RFC 8126           IANA Considerations Section in RFCs         June 2017   In many cases, if there are a number of registered references to the   original RFC and the document organization has not changed the   registered section numbering much, it may simply be reasonable to do   this:      Because this document obsoletesRFC 4637, IANA is asked to change      all registration information that references [RFC4637] to instead      reference [[this RFC]].   If information for registered items has been or is being moved to   other documents, then the registration information should be changed   to point to those other documents.  In most cases, documentation   references should not be left pointing to the obsoleted document for   registries or registered items that are still in current use.  For   registries or registered items that are no longer in current use, it   will usually make sense to leave the references pointing to the old   document -- the last current reference for the obsolete items.  The   main point is to make sure that the reference pointers are as useful   and current as is reasonable, and authors should consider that as   they write the IANA Considerations for the new document.  As always:   do the right thing, and there is flexibility to allow for that.   It is extremely important to be clear in your instructions regarding   updating references, especially in cases where some references need   to be updated and others do not.9.  Miscellaneous Issues9.1.  When There Are No IANA Actions   Before an Internet-Draft can be published as an RFC, IANA needs to   know what actions (if any) it needs to perform.  Experience has shown   that it is not always immediately obvious whether a document has no   IANA actions, without reviewing the document in some detail.  In   order to make it clear to IANA that it has no actions to perform (and   that the author has consciously made such a determination), such   documents should, after the authors confirm that this is the case,   include an IANA Considerations section that states:      This document has no IANA actions.   IANA prefers that these "empty" IANA Considerations sections be left   in the document for the record: it makes it clear later on that the   document explicitly said that no IANA actions were needed (and that   it wasn't just omitted).  This is a change from the prior practice of   requesting that such sections be removed by the RFC Editor, and   authors are asked to accommodate this change.Cotton, et al.            Best Current Practice                [Page 34]

RFC 8126           IANA Considerations Section in RFCs         June 20179.2.  Namespaces Lacking Documented Guidance   For all existing RFCs that either explicitly or implicitly rely on   IANA to make assignments without specifying a precise assignment   policy, IANA will work with the IESG to decide what policy is   appropriate.  Changes to existing policies can always be initiated   through the normal IETF consensus process, or through the IESG when   appropriate.   All future RFCs that either explicitly or implicitly rely on IANA to   register or otherwise administer namespace assignments must provide   guidelines for administration of the namespace.9.3.  After-the-Fact Registrations   Occasionally, the IETF becomes aware that an unassigned value from a   namespace is in use on the Internet or that an assigned value is   being used for a different purpose than it was registered for.  The   IETF does not condone such misuse; procedures of the type described   in this document need to be applied to such cases, and it might not   always be possible to formally assign the desired value.  In the   absence of specifications to the contrary, values may only be   reassigned for a different purpose with the consent of the original   assignee (when possible) and with due consideration of the impact of   such a reassignment.  In cases of likely controversy, consultation   with the IESG is advised.   This is part of the reason for the advice inSection 3.1 about using   placeholder values, such as "TBD1", during document development:   problems are often caused by the open use of unregistered values   after results from well-meant, early implementations, where the   implementations retained the use of developmental code points that   never proceeded to a final IANA assignment.9.4.  Reclaiming Assigned Values   Reclaiming previously assigned values for reuse is tricky, because   doing so can lead to interoperability problems with deployed systems   still using the assigned values.  Moreover, it can be extremely   difficult to determine the extent of deployment of systems making use   of a particular value.  However, in cases where the namespace is   running out of unassigned values and additional ones are needed, it   may be desirable to attempt to reclaim unused values.  When   reclaiming unused values, the following (at a minimum) should be   considered:Cotton, et al.            Best Current Practice                [Page 35]

RFC 8126           IANA Considerations Section in RFCs         June 2017   o  Attempts should be made to contact the original party to which a      value is assigned, to determine if the value was ever used, and if      so, the extent of deployment.  (In some cases, products were never      shipped or have long ceased being used.  In other cases, it may be      known that a value was never actually used at all.)   o  Reassignments should not normally be made without the concurrence      of the original requester.  Reclamation under such conditions      should only take place where there is strong evidence that a value      is not widely used, and the need to reclaim the value outweighs      the cost of a hostile reclamation.  IESG Approval is needed in      this case.   o  It may be appropriate to write up the proposed action and solicit      comments from relevant user communities.  In some cases, it may be      appropriate to write an RFC that goes through a formal IETF      process (including IETF Last Call) as was done when DHCP reclaimed      some of its "Private Use" options [RFC3942].   o  It may be useful to differentiate between revocation, release, and      transfer.  Revocation occurs when IANA removes an assignment,      release occurs when the assignee initiates that removal, and      transfer occurs when either revocation or release is coupled with      immediate reassignment.  It may be useful to specify procedures      for each of these or to explicitly prohibit combinations that are      not desired.9.5.  Contact Person vs Assignee or Owner   Many registries include designation of a technical or administrative   contact associated with each entry.  Often, this is recorded as   contact information for an individual.  It is unclear, though, what   role the individual has with respect to the registration: is this   item registered on behalf of the individual, the company the   individual worked for, or perhaps another organization the individual   was acting for?   This matters because some time later, when the individual has changed   jobs or roles, and perhaps can no longer be contacted, someone might   want to update the registration.  IANA has no way to know what   company, organization, or individual should be allowed to take the   registration over.  For registrations rooted in RFCs, the stream   owner (such as the IESG or the IAB) can make an overriding decision.   But in other cases, there is no recourse.   Registries can include, in addition to a "Contact" field, an   "Assignee" or "Owner" field (also referred to as "Change Controller")   that can be used to address this situation, giving IANA clearCotton, et al.            Best Current Practice                [Page 36]

RFC 8126           IANA Considerations Section in RFCs         June 2017   guidance as to the actual owner of the registration.  This is   strongly advised, especially for registries that do not require RFCs   to manage their information (e.g., registries with policies such as   First Come First Served (Section 4.4), Expert Review (Section 4.5),   and Specification Required (Section 4.6)).  Alternatively,   organizations can put an organizational role into the "Contact" field   in order to make their ownership clear.9.6.  Closing or Obsoleting a Registry/Registrations   Sometimes there is a request to "close" a registry to further   registrations.  When a registry is closed, no further registrations   will be accepted.  The information in the registry will still be   valid and registrations already in the registry can still be updated.   A closed registry can also be marked as "obsolete", as an indication   that the information in the registry is no longer in current use.   Specific entries in a registry can be marked as "obsolete" (no longer   in use) or "deprecated" (use is not recommended).   Such changes to registries and registered values are subject to   normal change controls (seeSection 2.3).  Any closure, obsolescence,   or deprecation serves to annotate the registry involved; the   information in the registry remains there for informational and   historic purposes.10.  Appeals   Appeals of protocol parameter registration decisions can be made   using the normal IETF appeals process as described in[RFC2026],   Section 6.5.  That is, an initial appeal should be directed to the   IESG, followed (if necessary) by an appeal to the IAB.11.  Mailing Lists   All IETF mailing lists associated with evaluating or discussing   assignment requests as described in this document are subject to   whatever rules of conduct and methods of list management are   currently defined by best current practices or by IESG decision.12.  Security Considerations   Information that creates or updates a registration needs to be   authenticated and authorized.  IANA updates registries according to   instructions in published RFCs and from the IESG.  It may also accept   clarifications from document authors, relevant working group chairs,   designated experts, and mail list participants.Cotton, et al.            Best Current Practice                [Page 37]

RFC 8126           IANA Considerations Section in RFCs         June 2017   Information concerning possible security vulnerabilities of a   protocol may change over time.  Likewise, security vulnerabilities   related to how an assigned number is used may change as well.  As new   vulnerabilities are discovered, information about such   vulnerabilities may need to be attached to existing registrations so   that users are not misled as to the true security issues surrounding   the use of a registered number.   Security needs to be considered as part of the selection of a   registration policy.  For some protocols, registration of certain   parameters will have security implications, and registration policies   for the relevant registries must ensure that requests get appropriate   review with those security implications in mind.   An analysis of security issues is generally required for all   protocols that make use of parameters (data types, operation codes,   keywords, etc.) documented in IETF protocols or registered by IANA.   Such security considerations are usually included in the protocol   document [BCP72].  It is the responsibility of the IANA   considerations associated with a particular registry to specify   whether value-specific security considerations must be provided when   assigning new values and the process for reviewing such claims.13.  IANA Considerations   Sitewide, IANA has replaced references toRFC 5226 with references to   this document.14.  Changes Relative to Earlier Editions ofBCP 2614.1.  2016: Changes in This Document Relative toRFC 5226   Significant additions:   o  RemovedRFC 2119 key words, boilerplate, and reference, preferring      plain English -- this is not a protocol specification.   o  AddedSection 1.1, Keep IANA Considerations for IANA   o  AddedSection 1.2, For Updated Information   o  AddedSection 2.1, Organization of Registries   o  Added best practice for selecting an appropriate policy intoSection 4.   o  AddedSection 4.12, Using Multiple Policies in CombinationCotton, et al.            Best Current Practice                [Page 38]

RFC 8126           IANA Considerations Section in RFCs         June 2017   o  AddedSection 2.3, Specifying Change Control for a Registry   o  AddedSection 3.4, Early Allocations   o  Moved each well-known policy into a separate subsection ofSection 4.   o  AddedSection 5.4, Expert Reviews and the Document Lifecycle   o  AddedSection 7, Documentation References in IANA Registries   o  AddedSection 8, What to Do in "bis" Documents   o  AddedSection 9.5, Contact Person vs Assignee or Owner   o  AddedSection 9.6, Closing or Obsoleting a Registry/Registrations   Clarifications and such:   o  Some reorganization -- moved text around for clarity and easier      reading.   o  Made clarifications about identification of IANA registries and      use of URLs for them.   o  Clarified the distinction between "Unassigned" and "Reserved".   o  Made some clarifications in "Expert Review" about instructions to      the designated expert.   o  Made some clarifications in "Specification Required" about how to      declare this policy.   o  Assorted minor clarifications and editorial changes throughout.14.2.  2008: Changes inRFC 5226 Relative toRFC 2434   Changes include:   o  Major reordering of text to expand descriptions and to better      group topics such as "updating registries" vs. "creating new      registries", in order to make it easier for authors to find the      text most applicable to their needs.   o  Numerous editorial changes to improve readability.Cotton, et al.            Best Current Practice                [Page 39]

RFC 8126           IANA Considerations Section in RFCs         June 2017   o  Changed the term "IETF Consensus" to "IETF Review" and added more      clarifications.  History has shown that people see the words "IETF      Consensus" (without consulting the actual definition) and are      quick to make incorrect assumptions about what the term means in      the context of IANA Considerations.   o  Added "RFC Required" to list of defined policies.   o  Much more explicit directions and examples of "what to put in      RFCs".   o  "Specification Required" now implies use of a designated expert to      evaluate specs for sufficient clarity.   o  Added a section describing provisional registrations.   o  Significantly changed the wording in the "Designated Experts"      section.  Main purpose is to make clear that Expert Reviewers are      accountable to the community, and to provide some guidance for      review criteria in the default case.   o  Changed wording to remove any special appeals path.  The normalRFC 2026 appeals path is used.   o  Added a section about reclaiming unused values.   o  Added a section on after-the-fact registrations.   o  Added a section indicating that mailing lists used to evaluate      possible assignments (such as by a designated expert) are subject      to normal IETF rules.15.  References15.1.  Normative References   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision              3",BCP 9,RFC 2026, DOI 10.17487/RFC2026, October 1996,              <http://www.rfc-editor.org/info/rfc2026>.15.2.  Informative References   [BCP72]    Rescorla, E. and B. Korver, "Guidelines for Writing RFC              Text on Security Considerations",BCP 72,RFC 3552, July              2003, <http://www.rfc-editor.org/info/bcp72>.Cotton, et al.            Best Current Practice                [Page 40]

RFC 8126           IANA Considerations Section in RFCs         June 2017   [RFC791]   Postel, J., "Internet Protocol", STD 5,RFC 791,              DOI 10.17487/RFC0791, September 1981,              <http://www.rfc-editor.org/info/rfc791>.   [RFC1591]  Postel, J., "Domain Name System Structure and Delegation",RFC 1591, DOI 10.17487/RFC1591, March 1994,              <http://www.rfc-editor.org/info/rfc1591>.   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an              IANA Considerations Section in RFCs",RFC 2434,              DOI 10.17487/RFC2434, October 1998,              <http://www.rfc-editor.org/info/rfc2434>.   [RFC2860]  Carpenter, B., Baker, F., and M. Roberts, "Memorandum of              Understanding Concerning the Technical Work of the              Internet Assigned Numbers Authority",RFC 2860,              DOI 10.17487/RFC2860, June 2000,              <http://www.rfc-editor.org/info/rfc2860>.   [RFC2939]  Droms, R., "Procedures and IANA Guidelines for Definition              of New DHCP Options and Message Types",BCP 43,RFC 2939,              DOI 10.17487/RFC2939, September 2000,              <http://www.rfc-editor.org/info/rfc2939>.   [RFC3228]  Fenner, B., "IANA Considerations for IPv4 Internet Group              Management Protocol (IGMP)",BCP 57,RFC 3228,              DOI 10.17487/RFC3228, February 2002,              <http://www.rfc-editor.org/info/rfc3228>.   [RFC3575]  Aboba, B., "IANA Considerations for RADIUS (Remote              Authentication Dial In User Service)",RFC 3575,              DOI 10.17487/RFC3575, July 2003,              <http://www.rfc-editor.org/info/rfc3575>.   [RFC3692]  Narten, T., "Assigning Experimental and Testing Numbers              Considered Useful",BCP 82,RFC 3692,              DOI 10.17487/RFC3692, January 2004,              <http://www.rfc-editor.org/info/rfc3692>.   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.              Levkowetz, Ed., "Extensible Authentication Protocol              (EAP)",RFC 3748, DOI 10.17487/RFC3748, June 2004,              <http://www.rfc-editor.org/info/rfc3748>.   [RFC3864]  Klyne, G., Nottingham, M., and J. Mogul, "Registration              Procedures for Message Header Fields",BCP 90,RFC 3864,              DOI 10.17487/RFC3864, September 2004,              <http://www.rfc-editor.org/info/rfc3864>.Cotton, et al.            Best Current Practice                [Page 41]

RFC 8126           IANA Considerations Section in RFCs         June 2017   [RFC3942]  Volz, B., "Reclassifying Dynamic Host Configuration              Protocol version 4 (DHCPv4) Options",RFC 3942,              DOI 10.17487/RFC3942, November 2004,              <http://www.rfc-editor.org/info/rfc3942>.   [RFC3968]  Camarillo, G., "The Internet Assigned Number Authority              (IANA) Header Field Parameter Registry for the Session              Initiation Protocol (SIP)",BCP 98,RFC 3968,              DOI 10.17487/RFC3968, December 2004,              <http://www.rfc-editor.org/info/rfc3968>.   [RFC4025]  Richardson, M., "A Method for Storing IPsec Keying              Material in DNS",RFC 4025, DOI 10.17487/RFC4025, March              2005, <http://www.rfc-editor.org/info/rfc4025>.   [RFC4044]  McCloghrie, K., "Fibre Channel Management MIB",RFC 4044,              DOI 10.17487/RFC4044, May 2005,              <http://www.rfc-editor.org/info/rfc4044>.   [RFC4124]  Le Faucheur, F., Ed., "Protocol Extensions for Support of              Diffserv-aware MPLS Traffic Engineering",RFC 4124,              DOI 10.17487/RFC4124, June 2005,              <http://www.rfc-editor.org/info/rfc4124>.   [RFC4169]  Torvinen, V., Arkko, J., and M. Naslund, "Hypertext              Transfer Protocol (HTTP) Digest Authentication Using              Authentication and Key Agreement (AKA) Version-2",RFC 4169, DOI 10.17487/RFC4169, November 2005,              <http://www.rfc-editor.org/info/rfc4169>.   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A              Border Gateway Protocol 4 (BGP-4)",RFC 4271,              DOI 10.17487/RFC4271, January 2006,              <http://www.rfc-editor.org/info/rfc4271>.   [RFC4283]  Patel, A., Leung, K., Khalil, M., Akhtar, H., and K.              Chowdhury, "Mobile Node Identifier Option for Mobile IPv6              (MIPv6)",RFC 4283, DOI 10.17487/RFC4283, November 2005,              <http://www.rfc-editor.org/info/rfc4283>.   [RFC4340]  Kohler, E., Handley, M., and S. Floyd, "Datagram              Congestion Control Protocol (DCCP)",RFC 4340,              DOI 10.17487/RFC4340, March 2006,              <http://www.rfc-editor.org/info/rfc4340>.Cotton, et al.            Best Current Practice                [Page 42]

RFC 8126           IANA Considerations Section in RFCs         June 2017   [RFC4422]  Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple              Authentication and Security Layer (SASL)",RFC 4422,              DOI 10.17487/RFC4422, June 2006,              <http://www.rfc-editor.org/info/rfc4422>.   [RFC4446]  Martini, L., "IANA Allocations for Pseudowire Edge to Edge              Emulation (PWE3)",BCP 116,RFC 4446,              DOI 10.17487/RFC4446, April 2006,              <http://www.rfc-editor.org/info/rfc4446>.   [RFC4520]  Zeilenga, K., "Internet Assigned Numbers Authority (IANA)              Considerations for the Lightweight Directory Access              Protocol (LDAP)",BCP 64,RFC 4520, DOI 10.17487/RFC4520,              June 2006, <http://www.rfc-editor.org/info/rfc4520>.   [RFC4589]  Schulzrinne, H. and H. Tschofenig, "Location Types              Registry",RFC 4589, DOI 10.17487/RFC4589, July 2006,              <http://www.rfc-editor.org/info/rfc4589>.   [RFC4727]  Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,              ICMPv6, UDP, and TCP Headers",RFC 4727,              DOI 10.17487/RFC4727, November 2006,              <http://www.rfc-editor.org/info/rfc4727>.   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security              (TLS) Protocol Version 1.2",RFC 5246,              DOI 10.17487/RFC5246, August 2008,              <http://www.rfc-editor.org/info/rfc5246>.   [RFC5378]  Bradner, S., Ed. and J. Contreras, Ed., "Rights              Contributors Provide to the IETF Trust",BCP 78,RFC 5378,              DOI 10.17487/RFC5378, November 2008,              <http://www.rfc-editor.org/info/rfc5378>.   [RFC5742]  Alvestrand, H. and R. Housley, "IESG Procedures for              Handling of Independent and IRTF Stream Submissions",BCP 92,RFC 5742, DOI 10.17487/RFC5742, December 2009,              <http://www.rfc-editor.org/info/rfc5742>.   [RFC5771]  Cotton, M., Vegoda, L., and D. Meyer, "IANA Guidelines for              IPv4 Multicast Address Assignments",BCP 51,RFC 5771,              DOI 10.17487/RFC5771, March 2010,              <http://www.rfc-editor.org/info/rfc5771>.   [RFC5795]  Sandlund, K., Pelletier, G., and L-E. Jonsson, "The RObust              Header Compression (ROHC) Framework",RFC 5795,              DOI 10.17487/RFC5795, March 2010,              <http://www.rfc-editor.org/info/rfc5795>.Cotton, et al.            Best Current Practice                [Page 43]

RFC 8126           IANA Considerations Section in RFCs         June 2017   [RFC6014]  Hoffman, P., "Cryptographic Algorithm Identifier              Allocation for DNSSEC",RFC 6014, DOI 10.17487/RFC6014,              November 2010, <http://www.rfc-editor.org/info/rfc6014>.   [RFC6230]  Boulton, C., Melanchuk, T., and S. McGlashan, "Media              Control Channel Framework",RFC 6230,              DOI 10.17487/RFC6230, May 2011,              <http://www.rfc-editor.org/info/rfc6230>.   [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility              Support in IPv6",RFC 6275, DOI 10.17487/RFC6275, July              2011, <http://www.rfc-editor.org/info/rfc6275>.   [RFC6698]  Hoffman, P. and J. Schlyter, "The DNS-Based Authentication              of Named Entities (DANE) Transport Layer Security (TLS)              Protocol: TLSA",RFC 6698, DOI 10.17487/RFC6698, August              2012, <http://www.rfc-editor.org/info/rfc6698>.   [RFC6709]  Carpenter, B., Aboba, B., Ed., and S. Cheshire, "Design              Considerations for Protocol Extensions",RFC 6709,              DOI 10.17487/RFC6709, September 2012,              <http://www.rfc-editor.org/info/rfc6709>.   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type              Specifications and Registration Procedures",BCP 13,RFC 6838, DOI 10.17487/RFC6838, January 2013,              <http://www.rfc-editor.org/info/rfc6838>.   [RFC6895]  Eastlake 3rd, D., "Domain Name System (DNS) IANA              Considerations",BCP 42,RFC 6895, DOI 10.17487/RFC6895,              April 2013, <http://www.rfc-editor.org/info/rfc6895>.   [RFC6994]  Touch, J., "Shared Use of Experimental TCP Options",RFC 6994, DOI 10.17487/RFC6994, August 2013,              <http://www.rfc-editor.org/info/rfc6994>.   [RFC7120]  Cotton, M., "Early IANA Allocation of Standards Track Code              Points",BCP 100,RFC 7120, DOI 10.17487/RFC7120, January              2014, <http://www.rfc-editor.org/info/rfc7120>.   [RFC7564]  Saint-Andre, P. and M. Blanchet, "PRECIS Framework:              Preparation, Enforcement, and Comparison of              Internationalized Strings in Application Protocols",RFC 7564, DOI 10.17487/RFC7564, May 2015,              <http://www.rfc-editor.org/info/rfc7564>.Cotton, et al.            Best Current Practice                [Page 44]

RFC 8126           IANA Considerations Section in RFCs         June 2017   [RFC7595]  Thaler, D., Ed., Hansen, T., and T. Hardie, "Guidelines              and Registration Procedures for URI Schemes",BCP 35,RFC 7595, DOI 10.17487/RFC7595, June 2015,              <http://www.rfc-editor.org/info/rfc7595>.   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and              S. Ray, "North-Bound Distribution of Link-State and              Traffic Engineering (TE) Information Using BGP",RFC 7752,              DOI 10.17487/RFC7752, March 2016,              <http://www.rfc-editor.org/info/rfc7752>.   [RFC8141]  Saint-Andre, P. and J. Klensin, "Uniform Resource Names              (URNs)",RFC 8141, DOI 10.17487/RFC8141, April 2017,              <http://www.rfc-editor.org/info/rfc8141>.Cotton, et al.            Best Current Practice                [Page 45]

RFC 8126           IANA Considerations Section in RFCs         June 2017Acknowledgments for This Document (2017)   Thomas Narten and Harald Tveit Alvestrand edited the two earlier   editions of this document (RFCs 2434 and 5226), and Thomas continues   his role in this third edition.  Much of the text fromRFC 5226   remains in this edition.   Thank you to Amanda Baber and Pearl Liang for their multiple reviews   and suggestions for making this document as thorough as possible.   This document has benefited from thorough review and comments by many   people, including Benoit Claise, Alissa Cooper, Adrian Farrel,   Stephen Farrell, Tony Hansen, John Klensin, Kathleen Moriarty, Mark   Nottingham, Pete Resnick, and Joe Touch.   Special thanks to Mark Nottingham for reorganizing some of the text   for better organization and readability, to Tony Hansen for acting as   document shepherd, and to Brian Haberman and Terry Manderson for   acting as sponsoring ADs.Acknowledgments from the Second Edition (2008)   The original acknowledgments section inRFC 5226 was:   This document has benefited from specific feedback from Jari Arkko,   Marcelo Bagnulo Braun, Brian Carpenter, Michelle Cotton, Spencer   Dawkins, Barbara Denny, Miguel Garcia, Paul Hoffman, Russ Housley,   John Klensin, Allison Mankin, Blake Ramsdell, Mark Townsley, Magnus   Westerlund, and Bert Wijnen.Acknowledgments from the First Edition (1998)   The original acknowledgments section inRFC 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 fromRFC 4288.Cotton, et al.            Best Current Practice                [Page 46]

RFC 8126           IANA Considerations Section in RFCs         June 2017Authors' Addresses   Michelle Cotton   PTI, an affiliate of ICANN   12025 Waterfront Drive, Suite 300   Los Angeles, CA  90094-2536   United States of America   Phone: +1-424-254-5300   Email: michelle.cotton@iana.org   URI:https://www.iana.org/   Barry Leiba   Huawei Technologies   Phone: +1 646 827 0648   Email: barryleiba@computer.org   URI:http://internetmessagingtechnology.org/   Thomas Narten   IBM Corporation   3039 Cornwallis Ave., PO Box 12195 - BRQA/502   Research Triangle Park, NC  27709-2195   United States of America   Phone: +1 919 254 7798   Email: narten@us.ibm.comCotton, et al.            Best Current Practice                [Page 47]