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.
Hoffman Standards Track [Page 1]
RFC 2987 Charset and Languages Media Features Tags November 2000 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 Hoffman Standards Track [Page 2]
RFC 2987 Charset and Languages Media Features Tags November 2000 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 Hoffman Standards Track [Page 3]
RFC 2987 Charset and Languages Media Features Tags November 2000 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. Hoffman Standards Track [Page 4]
RFC 2987 Charset and Languages Media Features Tags November 2000 6. Author's Address Paul Hoffman Internet Mail Consortium 127 Segre Place Santa Cruz, CA 95060 USA EMail: phoffman@imc.org Hoffman Standards Track [Page 5]
RFC 2987 Charset and Languages Media Features Tags November 2000 7. Full Copyright Statement Copyright (C) The Internet Society (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. 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 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. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Hoffman Standards Track [Page 6]
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