Tags for the Identification of Languages
RFC 3066

<new code> instead" to the
   "other relevant information" section.

   Note: The purpose of the "published description" is intended as an
   aid to people trying to verify whether a language is registered, or
   what language a particular tag refers to.  In most cases, reference
   to an authoritative grammar or dictionary of the language will be
   useful; in cases where no such work exists, other well known works
   describing that language or in that language may be appropriate.  The
   language tag reviewer decides what constitutes a "good enough"
   reference material.

4. Security Considerations

   The only security issue that has been raised with language tags since
   the publication of RFC 1766, which stated that "Security issues are
   believed to be irrelevant to this memo", is a concern with language
   ranges used in content negotiation - that they may be used to infer
   the nationality of the sender, and thus identify potential targets
   for surveillance.

   This is a special case of the general problem that anything you send
   is visible to the receiving party; it is useful to be aware that such
   concerns can exist in some cases.

   The evaluation of the exact magnitude of the threat, and any possible
   countermeasures, is left to each application protocol.

5. Character set considerations

   Language tags may always be presented using the characters A-Z, a-z,
   0-9 and HYPHEN-MINUS, which are present in most character sets, so
   presentation of language tags should not have any character set
   issues.

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   The issue of deciding upon the rendering of a character set based on
   the language tag is not addressed in this memo; however, it is
   thought impossible to make such a decision correctly for all cases
   unless means of switching language in the middle of a text are
   defined (for example, a rendering engine that decides font based on
   Japanese or Chinese language may produce suboptimal output when a
   mixed Japanese-Chinese text is encountered)

6. Acknowledgements

   This document has benefited from many rounds of review and comments
   in various fora of the IETF and the Internet working groups.

   Any list of contributors is bound to be incomplete; please regard the
   following as only a selection from the group of people who have
   contributed to make this document what it is today.

   In alphabetical order:

   Glenn Adams, Tim Berners-Lee, Marc Blanchet, Nathaniel Borenstein,
   Eric Brunner, Sean M. Burke, John Clews, Jim Conklin, Peter
   Constable, John Cowan, Mark Crispin, Dave Crocker, Mark Davis, Martin
   Duerst, Michael Everson, Ned Freed, Tim Goodwin, Dirk-Willem van
   Gulik, Marion Gunn, Paul Hoffman, Olle Jarnefors, Kent Karlsson, John
   Klensin, Alain LaBonte, Chris Newman, Keith Moore, Masataka Ohta,
   Keld Jorn Simonsen, Otto Stolz, Rhys Weatherley, Misha Wolf, Francois
   Yergeau and many, many others.

   Special thanks must go to Michael Everson, who has served as language
   tag reviewer for almost the complete period since the publication of
   RFC 1766, and has provided a great deal of input to this revision.

7. Author's Address

   Harald Tveit Alvestrand
   Cisco Systems
   Weidemanns vei 27
   7043 Trondheim
   NORWAY

   Phone: +47 73 50 33 52
   EMail: Harald@Alvestrand.no

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8. References

   [ISO 639]   ISO 639:1988 (E/F) - Code for the representation of names
               of languages - The International Organization for
               Standardization, 1st edition, 1988-04-01 Prepared by
               ISO/TC 37 - Terminology (principles and coordination).
               Note that a new version (ISO 639-1:2000) is in
               preparation at the time of this writing.

   [ISO 639-2] ISO 639-2:1998 - Codes for the representation of names of
               languages -- Part 2: Alpha-3 code  - edition 1, 1998-11-
               01, 66 pages, prepared by a Joint Working Group of ISO
               TC46/SC4 and ISO TC37/SC2.

   [ISO 3166]  ISO 3166:1988 (E/F) - Codes for the representation of
               names of countries - The International Organization for
               Standardization, 3rd edition, 1988-08-15.

   [RFC 1327]  Kille, S., "Mapping between X.400 (1988) / ISO 10021 and
               RFC 822", RFC 1327, May 1992.

   [RFC 1521]  Borenstein, N., and N. Freed, "MIME Part One: Mechanisms
               for Specifying and Describing the Format of Internet
               Message Bodies", RFC 1521, September 1993.

   [RFC 2026]  Bradner, S., "The Internet Standards Process -- Revision
               3", BCP 9, RFC 2026, October 1996.

   [RFC 2028]  Hovey, R. and S. Bradner, "The Organizations Involved in
               the IETF Standards Process", BCP 11, RFC 2028, October
               1996.

   [RFC 2119]  Bradner, S."Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC 2234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
               Specifications: ABNF", RFC 2234, November 1997.

   [RFC 2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
               Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
               Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC 2860]  Carpenter, B., Baker, F. and M. Roberts, "Memorandum of
               Understanding Concerning the Technical Work of the
               Internet Assigned Numbers Authority", RFC 2860, June
               2000.

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Appendix A: Language Tag Reference Material

   The Library of Congress, maintainers of ISO 639-2, has made the list
   of languages registered available on the Internet.

   At the time of this writing, it can be found at
   http://www.loc.gov/standards/iso639-2/langhome.html

   The IANA registration forms for registered language codes can be
   found at http://www.iana.org/numbers.html under "languages".

   The ISO 3166 Maintenance Agency has published Web pages at

   http://www.din.de/gremien/nas/nabd/iso3166ma/

Appendix B: Changes from RFC 1766

   - Email list address changed from ietf-types@uninett.no to ietf-
     languages@iana.org

   - Updated author's address

   - Added language-range construct from HTTP/1.1

   - Added use of ISO 639-2 language codes

   - Added reference to Library of Congress lists of language codes

   - Changed examples to use registered tags

   - Added "Any other information" to registration form

   - Added description of procedure for updating registrations

   - Changed target category for document from standards track to BCP

   - Moved the content-language header definition into another document

   - Added numbers to the permitted characters in language tags

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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.

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