    Network Working Group                                             H. Lie
    Request for Comments: 2318                                        B. Bos
    Category: Informational                                        C. Lilley
                                                                         W3C
                                                                  March 1998

                            The text/css Media Type

    Status of this Memo

       This memo provides information for the Internet community.  It does
       not specify an Internet standard of any kind.  Distribution of this
       memo is unlimited.

    Copyright Notice

       Copyright (C) The Internet Society (1998).  All Rights Reserved.

    Abstract

       Cascading Style Sheets (CSS) is a style sheet language for the World
       Wide Web. CSS style sheets have been in use since October 1995 using
       the Media Type text/css without registration; this memo seeks to
       regularize that position.

    1.  Introduction

       The World Wide Web Consortium has issued a Recommendation [1], which
       defines Cascading Style Sheets, level 1. This memo provides
       information about the text/css Media Type.

    2.  Cascading Style Sheets

       Cascading Style Sheets (CSS) is a style sheet language for the World
       Wide Web. It describes the presentation (e.g. fonts, colors and
       spacing) of structured documents. CSS is human readable and writable,
       and expresses style in common desktop publishing terminology.

       CSS style sheets have been in use since October 1995 using the Media
       Type text/css without registration; this memo seeks to regularize
       that position.

       A CSS style sheet can be either:

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       (1) external - the style sheet is linked to a document through a
           URI and exists as a separate object on the Web. The media type
           text/css is used when fetching the object, for example in the
           Content-Type and Accept header fields of HTTP [2].

       (2) internal - the style sheet is contained within the document. A
           typical scenario is an HTML [3] document that contains a style
           sheet within the STYLE element. Due to this close relationship,
           HTML and CSS share the same top-level name ("text").

    4.  Registration Information

           To: ietf-types@iana.org
           Subject: Registration of MIME media type text/css

           MIME media type name: text

           MIME subtype name: css

           Required parameters: none

           Optional parameters: charset

           The syntax of CSS is expressed in US-ASCII, but a CSS file can
           contain strings which may use any Unicode character. Any charset
           that is a superset of US-ASCII may be used; US-ASCII, iso-8859-X
           and utf-8 are recommended.

       Encoding considerations:

           For use with transports that are not 8-bit clean, quoted-
           printable encoding is recommended since the majority of
           characters will be CSS syntax and thus US-ASCII

       Security considerations:

           Applying a style sheet to a document may hide information
           otherwise visible. For example, a very small font size may be
           specified, or the display of certain document elements may be
           turned off.

           CSS style sheets consist of declarative property/value pairs
           assigned to element selectors. They contain no executable code.

           As with HTML documents, CSS style sheets may contain links to
           other media (images, sounds, fonts, other style sheets) and those
           links are typically followed automatically by software, resulting

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    RFC 2318                  text/css Media Type                 March 1998

           in the transfer of files without the explicit request of the user
           for each one. The security considerations of each linked file are
           those of the individual registered types.

       Interoperability considerations:

           CSS has proven to be widely interoperable across computer
           platforms, across Web browsers of different makes, and for import
           and export in multiple authoring tools.

       Published specification: see [1]

       Applications which use this media type:

           CSS is device-, platform- and vendor-neutral and is supported by
           a wide range of Web user agents and authoring tools for
           formatting HTML and XML documents.

       Additional information:

           Magic number(s): none
           File extension(s): .css
           Macintosh File Type Code(s): "css "
           Object Identifier(s) or OID(s): none

       Person & email address to contact for further information:

           The authors of this memo.

       Intended usage: COMMON

         Author/Change controller:

    5.  References

       [1]  Lie, H., and B. Bos, "Cascading Style Sheets, level 1",
            W3C Recommendation REC-CSS1-961217, http://www.w3.org/TR/REC-
            CSS1-961217, December 1996.

       [2]  Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T.
            Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC
            2068, January 1997.

       [3]  Raggett, D., Le Hors, A. and I. Jacobs, "HTML 4.0
            Specification", W3C Recommendation REC-html40-971218,
            http://www.w3.org/TR/REC-html40, December 1997.

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    6.  Authors' Addresses

       Hakon Lie
       W3C/INRIA
       2004, route des Lucioles - B.P. 93
       06902 Sophia Antipolis Cedex
       FRANCE

       Phone: +33 (0)492387771
       Fax:   +33 (0)493657765
       EMail: howcome@w3.org

       Bert Bos
       2004, route des Lucioles - B.P. 93
       06902 Sophia Antipolis Cedex
       FRANCE

       Phone: +33 (0)492387692
       Fax:   +33 (0)493657765
       EMail: bert@w3.org

       Chris Lilley
       2004, route des Lucioles - B.P. 93
       06902 Sophia Antipolis Cedex
       FRANCE

       Phone: +33 (0)492387987
       Fax:   +33 (0)493657765
       EMail: chris@w3.org

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    7.  Full Copyright Statement

       Copyright (C) The Internet Society (1998).  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 implmentation 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."

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