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:

   (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

       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.

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

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
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