MIME Content Types in Media Feature Expressions
RFC 2913

 
Document Type RFC - Proposed Standard (September 2000; No errata)
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Network Working Group                                           G. Klyne
Request for Comments: 2913                          Content Technologies
Category: Standards Track                                 September 2000

            MIME Content Types in Media Feature Expressions

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

   In "A Syntax for Describing Media Feature Sets", an expression format
   is presented for describing media feature capabilities using simple
   media feature tags.

   This memo defines a media feature tag whose value is a Multipurpose
   Internet Mail Extensions (MIME) content type.  This allows the
   construction of feature expressions that take account of the MIME
   content type of the corresponding data.

Table of Contents

   1. Introduction .................................................. 2
      1.1 Terminology and document conventions ...................... 2
   2. Motivation and goals .......................................... 3
   3. MIME content type feature tag ................................. 3
   4. Examples ...................................................... 4
      4.1 Simple text ............................................... 4
      4.2 Fax image ................................................. 4
      4.3 Voice message ............................................. 4
      4.4 Web browser capabilities .................................. 5
   5. IANA Considerations ........................................... 5
   6. Security Considerations ....................................... 5
   7. Acknowledgements .............................................. 5
   8. References .................................................... 6
   9. Author's Address .............................................. 6
   Appendix A: 'Type' feature tag registration ...................... 7
   Full Copyright Statement ......................................... 9

Klyne                       Standards Track                     [Page 1]
RFC 2913       MIME Content in Media Feature Expressions  September 2000

1. Introduction

   In "A Syntax for Describing Media Feature Sets" [1], an expression
   format is presented for describing media feature capabilities as a
   combination of simple media feature tags, registered according to
   "Media Feature Tag Registration Procedure" [2].  This provides a
   format for message handling agents to describe the media feature
   content of messages that they can handle.

   This memo defines a media feature tag whose value is a MIME content
   type.  This allows the construction of feature expressions that take
   account of the MIME content type of the corresponding data.

   Note that a content type feature value may contain parameters, but
   this is discouraged.  See section 3 and appendix A, "Summary of the
   media features indicated" for discussion of this point.

1.1 Terminology and document conventions

   This section defines a number of terms and other document
   conventions, which are used with specific meaning in this memo.

   media feature
         information that indicates facilities assumed to be available
         for the message content to be properly rendered or otherwise
         presented.  Media features are not intended to include
         information that affects message transmission.

   feature set
         some set of media features described by a media feature
         assertion, as described in "A Syntax for Describing Media
         Feature Sets" [1].  (See that memo for a more formal definition
         of this term.)

   feature set expression
         a string that describes some feature set, formulated according
         to the rules in "A Syntax for Describing Media Feature Sets"
         [1] (and possibly extended by other specifications).

   This specification uses syntax notation and conventions described in
   RFC 2234, "Augmented BNF for Syntax Specifications: ABNF" [3].

      NOTE:  Comments like this provide additional nonessential
      information about the rationale behind this document.  Such
      information is not needed for building a conformant
      implementation, but may help those who wish to understand the
      design in greater depth.

Klyne                       Standards Track                     [Page 2]
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