Network Working GroupG. Klyne
Internet-DraftMIMEsweeper Group
Expires: March 19, 2002Sep 18, 2001

A URN sub-namespace for language tags

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This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026.

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Copyright Notice

Copyright (C) The Internet Society (2001). All Rights Reserved.


1 This specification defines a form of URN to be used for language tags defined or registered according to RFC 3066. The URN namespace used is 'ietf', defined by RFC 2648 and extended by RFC????.


Table of Contents


1. Introduction

2 This specification defines a form of URN to be used for language tags defined or registered according to RFC 3066 [4]. The URN namespace used is 'IETF', defined by RFC 2648 [3] and extended by RFC???? [7] to include names for IETF protocol parameters.

1.1 Background

3 RFC 3066 [4] defines a construction and registry for tags used to identify human languages. These tags can be used to describe the language used by human-readable text, or other data intended for human prsentation.

4 [[[In the W3C work on RDF, [5], a generic XML metadata format that uses URIs to identify objects and the relationships between them, there has been some discussion about the identification of language for literal strings. Currently, RDF uses the XML attribute xml:lang, whose value is an RFC 3066 language tag, to identify the language of a literal. It is not clear how this can be represented in the abstract graph model of RDF. The normal form of identification used by RDF (and the Web in general) is a URI or URI-reference as defined by RFC 2396 [2].]]]

5 This specification defines a way to embed RFC 3066 language tags in a urn: form of URI, which can be used to identify a language in contexts where a URI is prefered to a text string or token.


2. Registration template

6 The URN sub-namespace for language tags is defined as follows.

Registry name:
7 language
8 RFC 3066
Index value:
10 The language tag name is the registry index value. RFC 3066 allows this tag name to contain uppercase letters, lowercase letters, digits, and dash ("-"). Language tags are case-insensitive.

Some allowed language tag values are defined by reference to ISO standard 639 [6].
URN formation:
11 The URN for a language tag is formed as: "urn:ietf:params:languiage:<tag-name>", where <tag-name> is the language registry index value.

RFC 2141 [1] defines the format of URNs. Allowable characters include all of those noted above.

URNs are defined by RFC 2141 [1] as lexically equivalent if they are identical following case normalization of the urn scheme name, the namespace name and any %-escaping used. Language tags are defined such that upper- and lower-case ASCII characters are not distinguished. In forming a URN, all ASCII characters in the language tag must be expressed in lower case.


3. Examples

12 This table lists some language tags, and the corresponding urn: URIs.

MN (Mongolian)
13 urn:ietf:params:language:mn
en-US (American English)
14 urn:ietf:params:language:en-us
zh-yue (Cantonese)
15 urn:ietf:params:language:zh-yue
sgn-GB (British sign language)
16 urn:ietf:params:language:sgn-gb
17 urn:ietf:params:language:i-klingon
18 urn:ietf:params:language:i-default
19 urn:ietf:params:language:x-private


4. IANA considerations

20 This document calls for the creation of a new IETF sub-namespace per RFC???? [7]. Registration details are in the preceding section.


5. Security considerations

21 No security considerations are introduced by this specification beyond those already inherrent in the use of language tags [4].



[1] Moats, R., "URN Syntax", RFC 2141, May 1997.
[2] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998.
[3] Moats, R., "A URN Namespace for IETF Documents", RFC 2648, August 1999.
[4] Alvestrand, H., "Tags for the Identification of Languages", BCP 47, RFC 3066, January 2001.
[5] Lassila, O. and R. Swick, "Resource Description Framework (RDF) Model and Syntax Specification", W3C Recommendation rdf-syntax, February 1999.
[6] International Organization for Standardization, "Code for the representation of names of languages, 1st edition", ISO Standard 639, 1988.
[7] Mealling, M., Masinter, L., Hardie, T. and G. Klyne, "An IETF URN Sub-namespace for Registered Protocol Parameters", August 2001.


Author's Address

  Graham Klyne
  MIMEsweeper Group
  1310 Waterside
  Arlington Business Park
  Theale, Reading RG7 4SA
Phone:  +44 118 903 8000
Fax:  +44 118 903 9000


Appendix A. Revision history

27 (This section to be removed on final publication)

A.1 draft-klyne-urn-ietf-lang-00


29 18-Sep-2001: document initially created.


Appendix B. Todo

30 (This section to be removed on final publication)


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