Tags for Identifying Languages
RFC 5646
| Document | Type |
RFC - Best Current Practice
(September 2009; No errata)
Obsoletes RFC 4646
Also known as BCP 47
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5646 (Best Current Practice) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Alexey Melnikov | ||
| Send notices to | (None) | ||
Network Working Group A. Phillips, Ed.
Request for Comments: 5646 Lab126
BCP: 47 M. Davis, Ed.
Obsoletes: 4646 Google
Category: Best Current Practice September 2009
Tags for Identifying Languages
Abstract
This document describes the structure, content, construction, and
semantics of language tags for use in cases where it is desirable to
indicate the language used in an information object. It also
describes how to register values for use in language tags and the
creation of user-defined extensions for private interchange.
Status of This Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Please review these documents carefully, as they describe your rights
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This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
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material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Phillips & Davis Best Current Practice [Page 1]
RFC 5646 Language Tags September 2009
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. The Language Tag . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.1. Formatting of Language Tags . . . . . . . . . . . . . 6
2.2. Language Subtag Sources and Interpretation . . . . . . . . 8
2.2.1. Primary Language Subtag . . . . . . . . . . . . . . . . 9
2.2.2. Extended Language Subtags . . . . . . . . . . . . . . 11
2.2.3. Script Subtag . . . . . . . . . . . . . . . . . . . . 12
2.2.4. Region Subtag . . . . . . . . . . . . . . . . . . . . 13
2.2.5. Variant Subtags . . . . . . . . . . . . . . . . . . . 15
2.2.6. Extension Subtags . . . . . . . . . . . . . . . . . . 16
2.2.7. Private Use Subtags . . . . . . . . . . . . . . . . . 18
2.2.8. Grandfathered and Redundant Registrations . . . . . . 18
2.2.9. Classes of Conformance . . . . . . . . . . . . . . . . 19
3. Registry Format and Maintenance . . . . . . . . . . . . . . . 21
3.1. Format of the IANA Language Subtag Registry . . . . . . . 21
3.1.1. File Format . . . . . . . . . . . . . . . . . . . . . 21
3.1.2. Record and Field Definitions . . . . . . . . . . . . . 23
3.1.3. Type Field . . . . . . . . . . . . . . . . . . . . . . 26
3.1.4. Subtag and Tag Fields . . . . . . . . . . . . . . . . 26
3.1.5. Description Field . . . . . . . . . . . . . . . . . . 26
3.1.6. Deprecated Field . . . . . . . . . . . . . . . . . . . 28
3.1.7. Preferred-Value Field . . . . . . . . . . . . . . . . 28
3.1.8. Prefix Field . . . . . . . . . . . . . . . . . . . . . 31
3.1.9. Suppress-Script Field . . . . . . . . . . . . . . . . 32
3.1.10. Macrolanguage Field . . . . . . . . . . . . . . . . . 32
3.1.11. Scope Field . . . . . . . . . . . . . . . . . . . . . 33
3.1.12. Comments Field . . . . . . . . . . . . . . . . . . . . 34
3.2. Language Subtag Reviewer . . . . . . . . . . . . . . . . . 35
3.3. Maintenance of the Registry . . . . . . . . . . . . . . . 35
3.4. Stability of IANA Registry Entries . . . . . . . . . . . . 36
3.5. Registration Procedure for Subtags . . . . . . . . . . . . 41
3.6. Possibilities for Registration . . . . . . . . . . . . . . 46
3.7. Extensions and the Extensions Registry . . . . . . . . . . 49
3.8. Update of the Language Subtag Registry . . . . . . . . . . 52
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