RFC 5131

A MIB Textual Convention for Language Tags

📅 published December 2007, from ietf

RFC 5131: A MIB Textual Convention for Language Tags ✨

Okay bestie, here's the vibe check 💖 This is RFC 5131, titled "A MIB Textual Convention for Language Tags." It was written by D. McWalter, Ed. at Data Connection Ltd, it's on the Standards Track 🎀, and it's dated December 2007. The title block doesn't list anything it obsoletes or updates, so nothing gets replaced or patched here 🦋

Status of This Memo 🌸

This document specifies an Internet standards track protocol for the Internet community, and asks for discussion and suggestions for improvements. For the standardization state and status of this protocol, check the current edition of the "Internet Official Protocol Standards" (STD 1). Distribution of this memo is unlimited.

Abstract 🧚

This MIB module defines a textual convention for representing BCP 47 language tags. The plan is for other MIB modules that would otherwise make their own representation to import this textual convention and use it instead 💅

Table of Contents 📚

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.  The Internet-Standard Management Framework  . . . . . . . . . . 2
4.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 4
8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
  8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 4
  8.2.  Informative References  . . . . . . . . . . . . . . . . . . 5

1. Introduction 🌈

Okay so this memo defines a piece of the Management Information Base (MIB) for network management protocols in the Internet community. The main thing it does is define a textual convention for BCP 47 [RFC4646] language tags 🎀

The LangTag TEXTUAL-CONVENTION in this RFC replaces the similar LanguageTag TEXTUAL-CONVENTION from RFC 2932 [RFC2932]. The old one is still used by some existing MIB modules. But new MIB modules should use LangTag, and it's the one to prefer because:

  • Its syntax description is current and more comprehensive. 💅
  • It's short enough to use as an index object without subtyping, but still long enough to hold any language tag you'll actually see in practice. 🔥
  • It lives in a dedicated MIB module, which keeps module dependencies simple. ✨

Here's the tea ☕ You can't change the syntax and length of an existing textual convention, so making a new one with a new name was the only way to do this 😭

2. Terminology 💜

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Those words are the whole rulebook for this doc, so read them carefully 🫶

3. The Internet-Standard Management Framework 🦋

If you want the big-picture tour of the documents behind the current Internet-Standard Management Framework, check out section 7 of RFC 3410 [RFC3410] 🌸

Managed objects live in a virtual information store called the Management Information Base, or MIB. You usually reach MIB objects through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the Structure of Management Information (SMI). This memo specifies a MIB module that complies with SMIv2, which is described in STD 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580 [RFC2580] 🧚

4. Definitions 🍓

Here's the actual MIB module, copied exactly as written 👑

LANGTAG-TC-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, mib-2             FROM SNMPv2-SMI      -- [RFC2578]
    TEXTUAL-CONVENTION                 FROM SNMPv2-TC;      -- [RFC2579]

langTagTcMIB MODULE-IDENTITY
    LAST-UPDATED "200711090000Z" -- 9 November 2007
    ORGANIZATION "IETF Operations and Management (OPS) Area"
    CONTACT-INFO "EMail: ops-area@ietf.org
                  Home page: http://www.ops.ietf.org/"
    DESCRIPTION
            "This MIB module defines a textual convention for
            representing BCP 47 language tags."
    REVISION     "200711090000Z" -- 9 November 2007
    DESCRIPTION
           "Initial revision, published as RFC 5131.

            Copyright (C) The IETF Trust (2007).  This version of this
            MIB module is part of RFC 5131; see the RFC itself for full
            legal notices."
    ::= { mib-2 165 }

LangTag ::= TEXTUAL-CONVENTION
   DISPLAY-HINT "1a"
   STATUS      current
   DESCRIPTION
            "A language tag, constructed in accordance with BCP 47.

            Only lowercase characters are allowed.  The purpose of this
            restriction is to provide unique language tags for use as
            indexes.  BCP 47 recommends case conventions for user
            interfaces, but objects using this TEXTUAL-CONVENTION MUST
            use only lowercase.

            Values MUST be well-formed language tags, in conformance
            with the definition of well-formed tags in BCP 47.  An
            implementation MAY further limit the values it accepts to
            those permitted by a 'validating' processor, as defined in
            BCP 47.

            In theory, BCP 47 language tags are of unlimited length.
            The language tag described in this TEXTUAL-CONVENTION is of
            limited length.  The analysis of language tag lengths in BCP
            47 confirms that this limit will not pose a problem in
            practice.  In particular, this length is greater than the
            minimum requirements set out in Section 4.3.1.

            A zero-length language tag is not a valid language tag.
            This can be used to express 'language tag absent' where
            required, for example, when used as an index field."
   REFERENCE "RFC 4646 BCP 47"
   SYNTAX      OCTET STRING (SIZE (0 | 2..63))

END

Quick tea on the LangTag bit: the lowercase rule is there so each tag is unique when used as an index. Tags have to be well-formed per BCP 47, and any implementation can optionally be stricter with a "validating" processor. In theory BCP 47 tags have no length limit, but this one does, and the RFC says that limit won't be a problem in practice 💅 A zero-length tag isn't valid, but it can stand in for "language tag absent" as an index field 🙈

5. Security Considerations 💀

This MIB module doesn't define any management objects. Instead, it defines a textual convention that other MIB modules may import and use for object definitions.

Meaningful security considerations can only be written in the MIB modules that actually define management objects. So this document has no impact on the security of the Internet. Phew 🫶

6. IANA Considerations 🌸

LANGTAG-TC-MIB is rooted under the mib-2 subtree. IANA has assigned { mib-2 165 } to the LANGTAG-TC-MIB module specified in this document 🎀

7. Acknowledgements 🫶

This MIB module is a reworking of existing material from RFC 2932.

It was generated by editing together contributions from Randy Presuhn, Dan Romascanu, Bill Fenner, Juergen Schoenwaelder, Bert Wijnen, Doug Ewell, and Ira McDonald. Huge thanks to all of them 👑

8. References 📖

8.1. Normative References

  • [RFC2119]: Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
  • [RFC2578]: McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
  • [RFC2579]: McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999.
  • [RFC2580]: McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999.
  • [RFC4646]: Phillips, A. and M. Davis, "Tags for Identifying Languages", BCP 47, RFC 4646, September 2006.

8.2. Informative References

  • [RFC2932]: McCloghrie, K., Farinacci, D., and D. Thaler, "IPv4 Multicast Routing MIB", RFC 2932, October 2000.
  • [RFC3410]: Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction and Applicability Statements for Internet-Standard Management Framework", RFC 3410, December 2002.

Author's Address 🎀

David McWalter (editor)
Data Connection Ltd
100 Church Street
Enfield  EN2 6BQ
United Kingdom

EMail: dmcw@dataconnection.com

Copyright (C) The IETF Trust (2007).

This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights.

This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Intellectual Property 🧚

The IETF takes no position on the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document, or on whether any license under such rights might or might not be available. It also doesn't claim to have made any independent effort to identify any such rights. Info on the procedures for rights in RFC documents can be found in BCP 78 and BCP 79.

Copies of IPR disclosures made to the IETF Secretariat, and any assurances of licenses to be made available, or the result of an attempt to get a general license or permission for implementers or users to use such proprietary rights, can be found in the IETF online IPR repository at http://www.ietf.org/ipr.

The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology required to implement this standard. Send that info to the IETF at ietf-ipr@ietf.org 💜

📦 where this page comes from