YANG module file name convention
draft-ietf-netmod-yang-module-filename-14

NETMOD Working Group                                        P. Andersson
Internet-Draft                                             Ionio Systems
Updates: 6020, 7950, 9907 (if approved)                      4 June 2026
Intended status: Standards Track                                        
Expires: 6 December 2026

                    YANG module file name convention
               draft-ietf-netmod-yang-module-filename-14

Abstract

   This document defines the YANG module file name convention.  The
   convention extends the YANG module file name using revision-date,
   with the YANG semantic version extension.  The YANG semantic version
   extension allows for an informative version to be associated with a
   particular YANG module revision.

   This document updates RFCs 6020, 7950, and 9907.

Status of This Memo

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

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

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

   This Internet-Draft will expire on 6 December 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Andersson                Expires 6 December 2026                [Page 1]
Internet-Draft      YANG Module File Name Convention           June 2026

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
     1.2.  Motivation  . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  YANG Module File Names  . . . . . . . . . . . . . . . . . . .   3
     2.1.  Code Components . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Coexistence with YANG Semver  . . . . . . . . . . . . . .   5
   3.  Operational Considerations  . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Known Incompatibilities  . . . . . . . . . . . . . .   7
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   This document defines the YANG module file name convention.  It
   extends the current convention defined in [RFC6020], [RFC7950], and
   [RFC9907], which uses revision-date, with the YANG semantic version
   extension defined in [I-D.ietf-netmod-yang-semver].

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

Andersson                Expires 6 December 2026                [Page 2]
Internet-Draft      YANG Module File Name Convention           June 2026

1.2.  Motivation

   Using YANG semantic version instead of revision date conveys
   additional information to the user.  A revision date only tells the
   user that it has been updated, while, for instance, a YANG Semver
   version can tell the user about the module's compatibility level at a
   glance.  Having this information available in the module file name,
   makes it possible to quickly identify the module revision without
   searching in the file contents and checking the revisions.  Having
   the YANG semantic version visible in the file name will make it
   easier to handle large sets of YANG modules.

2.  YANG Module File Names

   This section updates Section 5.2 of [RFC7950] and Section 5.2 of
   [RFC6020] by extending the file layout specification to also cover
   when a revision has an associated YANG semantic version.  Nothing
   else is modified in these sections.

   If a revision has an associated YANG semantic version (ysv:version)
   then a YANG file SHOULD be created that uses the YANG semantic
   version in the file name.  Additionally, YANG files with or without
   the revision-date MAY be created.  The name of the files SHOULD be of
   the form:

       module-or-submodule-name ['@' (ysv:version) / (revision-date)]
           ( '.yang' / '.yin' )

   E.g., acme-router-module@2.0.3.yang,
   acme-router-module@2024-05-15.yang, or acme-router-module.yang.

   Due to limitations of tooling, requirements of interoperability with
   legacy systems, and deployed system limitations, it might be
   difficult or impractical to use the file name convention defined in
   this document.  In such cases it is acceptable to not use the YANG
   module file name convention.

   The ysv:version in the file name MUST match the ysv:version in the
   most recent revision of the YANG module.

   Even though the ysv:version and the file name must match, the
   authorative source for the ysv:version is the contents in the YANG
   module, not the file name.

   Note that several files might be created as a consequence of using
   ysv:version or revision-date.  For instance a YANG module without
   ysv:version can be defined in either "module.yang",

Andersson                Expires 6 December 2026                [Page 3]
Internet-Draft      YANG Module File Name Convention           June 2026

   "module@2020-02-20.yang", or both.  A YANG module with ysv:version
   can be represented by "module@1.0.0.yang", "module@2026-06-02.yang",
   "module.yang".  The contents of the YANG modules for the same
   revision MUST be identical byte-for-byte.

   In short, the YANG semantic version file name scheme is RECOMMENDED,
   as its use will convey compatibility status at a glance without the
   need to read the module.  If a system or tooling can't handle the
   YANG module file name convention, it is acceptable to not support or
   use the convention defined in this document.

2.1.  Code Components

   This section updates Section 3.2 of [RFC9907] by extending the code
   component guidance to also cover when a revision has a ysv:version.
   Nothing else is modified in that section.

   If a revision has a ysv:version, the "<CODE BEGINS>" tag MUST be
   followed by a file name specified in this section.  The name string
   form that include the ysv:version SHOULD be used.  The ysv:version in
   the file name MUST match the ysv:version used in the most recent
   revision date.

   The following example is for the "2026-06-02" revision of the "ietf-
   foo" module, with ysv:version "1.0.0":

   <CODE BEGINS> file "ietf-foo@1.0.0.yang"

           module ietf-foo {
             namespace "urn:ietf:params:xml:ns:yang:ietf-foo";
             prefix "foo";
             organization "...";
             contact "...";
             description "...";
             revision 2026-06-02 {
               ysv:version 1.0.0;
               description "Latest revision";
               reference "RFC FFFF: Foo Protocol";
             }
             // ... more statements
           }

   <CODE ENDS>

Andersson                Expires 6 December 2026                [Page 4]
Internet-Draft      YANG Module File Name Convention           June 2026

2.2.  Coexistence with YANG Semver

   All valid identifiers for YANG semantic version are valid in the file
   name as well.  See more details for YANG Semver identifiers in
   Section 4.3 of [I-D.ietf-netmod-yang-semver].

   The following example is a valid YANG module file name

       example-module@2.3.1_non_compatible+build2237refM443ss.yang

   There might exist two modules derived from version 2.0.0 with the
   same X.Y.Z digits (2.0.1) but different version labels:

       2.0.1-draft-superman-super-stuff-03

       2.0.1-draft-batman-cool-addition-07   (a competing draft)

3.  Operational Considerations

   The delimiter symbol for YANG Semver is "@", the at sign (ASCII code
   decimal 64).  The same symbol is also used for revision-date.  The
   patterns for YANG Semver and revision-date will never match the same
   string, and it is easy to visually identify each of the conventions.

   The YANG module file name convention does not impact modules already
   in use.

   Tooling might need updates to handle the YANG module file name
   convention defined in this document.  In most cases this should be a
   small effort.  When migrating to the YANG module file name
   convention, different methods can be used to support existing files
   and new files.  An example is the use of symlinks with the file name
   defined in this document to existing files can be used when migrating
   existing YANG modules to the YANG module file name convention.

4.  IANA Considerations

   For complete guidance on how to handle YANG modules in RFCs and IANA
   registries, with regards to [I-D.ietf-netmod-yang-module-versioning],
   [I-D.ietf-netmod-yang-semver], and YANG module file names, see
   [I-D.ietf-netmod-iana-yang-guidance].

   The "YANG Module Names" registry under "YANG Parameters" registry
   group need to support YANG modules with both the existing file name
   convention and the file name convention defined in this document.

Andersson                Expires 6 December 2026                [Page 5]
Internet-Draft      YANG Module File Name Convention           June 2026

   The IANA action is to update the registry to support the YANG module
   file name convention.  If a YANG module (or submodule) has an
   associated YANG semantic version (ysv:version) a file name including
   it is listed.  Additionally, a file name with revision-date is listed
   for the YANG module (or submodule).  Files with the same revision are
   identical byte-for-byte.

5.  Security Considerations

   There are no security considerations for this document.

6.  References

6.1.  Normative References

   [I-D.ietf-netmod-yang-module-versioning]
              Wilton, R., Rahman, R., Lengyel, B., Clarke, J., and J.
              Sterne, "Updated YANG Module Revision Handling", Work in
              Progress, Internet-Draft, draft-ietf-netmod-yang-module-
              versioning-16, 21 April 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netmod-
              yang-module-versioning-16>.

   [I-D.ietf-netmod-yang-semver]
              Clarke, J., Wilton, R., Rahman, R., Lengyel, B., Sterne,
              J., and B. Claise, "YANG Semantic Versioning", Work in
              Progress, Internet-Draft, draft-ietf-netmod-yang-semver-
              26, 7 May 2026, <https://datatracker.ietf.org/doc/html/
              draft-ietf-netmod-yang-semver-26>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Andersson                Expires 6 December 2026                [Page 6]
Internet-Draft      YANG Module File Name Convention           June 2026

   [RFC9907]  Bierman, A., Boucadair, M., Ed., and Q. Wu, "Guidelines
              for Authors and Reviewers of Documents Containing YANG
              Data Models", BCP 216, RFC 9907, DOI 10.17487/RFC9907,
              March 2026, <https://www.rfc-editor.org/info/rfc9907>.

6.2.  Informative References

   [I-D.ietf-netmod-iana-yang-guidance]
              Wilton, R., "Guidance for Managing YANG Modules in RFCs
              and IANA Registries", Work in Progress, Internet-Draft,
              draft-ietf-netmod-iana-yang-guidance-02, 14 April 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netmod-
              iana-yang-guidance-02>.

Appendix A.  Known Incompatibilities

   RFC Ed: This note is to be removed before publishing as an RFC.

   There are currently no known publicly available tools that support
   the YANG semantic version file name schema.  There are known
   proprietary tooling that already uses the file name schema presented
   in this document.

   At the IETF 119 Hackathon, there was a project that investigated the
   feasibility to modify popular YANG tooling to support the proposed
   schema.  There was a successful attempt to modify pyang to support
   the file name schema and also "recommended-min" previously included
   in [I-D.ietf-netmod-yang-module-versioning].  Furthermore, there were
   efforts in researching yanger and libyang to support the schema, but
   the hackathon ended before these projects could be concluded.

Acknowledgements

   The author would like to thank Joe Clarke, Reshad Rahman, Mahesh
   Jethanandani, David Dong, Aihua Guo, Barry Leiba, Joel M.  Halpern,
   Meir Goldman, Carsten Bormann, and Kent Watsen for their excellent
   technical reviews, support, and guidance.

Author's Address

   Per Andersson
   Ionio Systems
   Email: per.ietf@ionio.se

Andersson                Expires 6 December 2026                [Page 7]