Network Working Group                                         P. Hoffman
Request for Comments: 2987                      Internet Mail Consortium
Category: Standards Track                                  November 2000


       Registration of Charset and Languages Media Features Tags

Status of this Memo

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

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.


Abstract

   This document contains the registration for two media feature tags:
   "charset" and "language".  These media features allow specification
   of character sets and human languages that can be understood by
   devices and the devices' users.  The templates in this document are
   derived from RFC 2506.

1. Registration for charset

   To: media-feature-tags@apps.ietf.org (Media feature tags mailing list)
   Subject: Registration of media feature tag charset

   Media feature tag name:
      charset

   ASN.1 identifier associated with feature tag:
      1.3.6.1.8.1.31

   Summary of the media feature indicated by this feature tag:
      Ability to display particular charsets as defined in [CHARSET].
           For most devices, this media feature is usually a capability;
           that is, most devices cannot intelligently process text in a
           charset that is unknown to the device.

   Values appropriate for use with this feature tag:
      The values are tokens as defined in [CHARSET].  The values can
           only be compared for equality.  Comparison is not case
           sensitive.

   The feature tag is intended primarily for use in the following
   applications, protocols, services, or negotiation mechanisms:
       Any protocol that uses media tags

   Examples of typical use:
      (| (charset=utf-8);q=1.0 (charset=iso-8859-1);q=0.9
         (charset=utf-16);q=0.5 )

   Related standards or documents:
      "IANA Charset Registration Procedures", RFC 2978

   Considerations particular to use in individual applications,
   protocols, services, or negotiation mechanisms:
      None

   Interoperability considerations: Aliases for charsets should not be
           used in media feature expressions because feature expression
           manipulation tools may convert aliases to the the principal
           name for the charset.  Even though charset names are not
           case-sensitive, values should be expressed as all lowercase
           letters to increase the likelihood of interoperability.  The
           "charset" capability should always be indicated in
           conjunction with any capability to handle textual data.

   Security considerations:
      If it is known that there is a security bug in the display of a
      particular charset in a particular environment, knowing that a
      device can accept that charset may slightly help an attacker.

   Additional information:
      None

   Name(s) & email address(es) of person(s) to contact for further
      information:
      Paul Hoffman <phoffman@imc.org>

   Intended usage:
      COMMON

   Author/Change controller:
      IETF

   Requested IANA publication delay:
      None

   Other information:
      None

2. Registration for language

   To: media-feature-tags@apps.ietf.org (Media feature tags mailing list)
   Subject: Registration of media feature tag language

   Media feature tag name:
      language

   ASN.1 identifier associated with feature tag:
      1.3.6.1.8.1.32

   Summary of the media feature indicated by this feature tag:  Ability
      to display particular human languages as defined in [LANG].  Note
      that "display" in this case will most often mean speech by a
      computer.  For most devices, this media feature is a preference,
      not a requirement.

   Values appropriate for use with this feature tag:
      The values are tokens, with allowable values defined by
           registration as defined in [LANG].  The values can only be
           compared for equality.  As described in [LANG], language tags
           are always handled as a single token, and "subtags" are not
           used for comparison.  Comparison is not case sensitive.

   The feature tag is intended primarily for use in the following
   applications, protocols, services, or negotiation mechanisms:
       Any protocol that uses media tags

   Examples of typical use:
      (| (language=no-nynorsk);q=1.0 (language=no-bokmaal);q=0.9
         (language=i-sami-no);q=0.5 )

   Related standards or documents:
      "Tags for the Identification of Languages", RFC 1766

   Considerations particular to use in individual applications,
   protocols, services, or negotiation mechanisms:
      None

   Interoperability considerations:
      Even though language tags are not case-sensitive, values should be
           expressed as all lowercase letters to increase the likelihood
           of interoperability.

   Security considerations:
      If it is known that there is a security bug in the display of a
      particular language in a particular environment, knowing that a
      device can accept that language may slightly help an attacker.

   Additional information:
      None

   Name(s) & email address(es) of person(s) to contact for further
   information:
      Paul Hoffman <phoffman@imc.org>

   Intended usage:
      COMMON

   Author/Change controller:
       IETF

   Requested IANA publication delay:
       None

   Other information:
       None

3. Security Considerations

   The security considerations are listed in the two registrations above.

4. IANA Considerations

   The bulk of this document is IANA registrations.

5. References

   [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration
             Procedures", BCP 19, RFC 2978, October 2000.

   [LANG]    Alvestrand, H., "Tags for the Identification of Languages",
             RFC 1766, March 1995.

   [TAG-REG] Holtman, K., Mutz, A. and T. Hardie, "Media Feature Tag
             Registration Procedure", BCP 31, RFC 2506, March 1999.

6. Author's Address

   Paul Hoffman
   Internet Mail Consortium
   127 Segre Place
   Santa Cruz, CA  95060 USA

   EMail: phoffman@imc.org

7.  Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

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   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
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   document itself may not be modified in any way, such as by removing
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   The limited permissions granted above are perpetual and will not be
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   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgement

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