RFC 2046 (rfc2046) - Page 2 of 44

Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types

RFC 2046                      Media Types                  November 1996


   data in Internet mail header fields. The fourth document, RFC 2048,
   specifies various IANA registration procedures for MIME-related
   facilities.  The fifth and final document, RFC 2049, describes MIME
   conformance criteria as well as providing some illustrative examples
   of MIME message formats, acknowledgements, and the bibliography.

   These documents are revisions of RFCs 1521 and 1522, which themselves
   were revisions of RFCs 1341 and 1342.  An appendix in RFC 2049
   describes differences and changes from previous versions.

Table of Contents

   1. Introduction .........................................    3
   2. Definition of a Top-Level Media Type .................    4
   3. Overview Of The Initial Top-Level Media Types ........    4
   4. Discrete Media Type Values ...........................    6
   4.1 Text Media Type .....................................    6
   4.1.1 Representation of Line Breaks .....................    7
   4.1.2 Charset Parameter .................................    7
   4.1.3 Plain Subtype .....................................   11
   4.1.4 Unrecognized Subtypes .............................   11
   4.2 Image Media Type ....................................   11
   4.3 Audio Media Type ....................................   11
   4.4 Video Media Type ....................................   12
   4.5 Application Media Type ..............................   12
   4.5.1 Octet-Stream Subtype ..............................   13
   4.5.2 PostScript Subtype ................................   14
   4.5.3 Other Application Subtypes ........................   17
   5. Composite Media Type Values ..........................   17
   5.1 Multipart Media Type ................................   17
   5.1.1 Common Syntax .....................................   19
   5.1.2 Handling Nested Messages and Multiparts ...........   24
   5.1.3 Mixed Subtype .....................................   24
   5.1.4 Alternative Subtype ...............................   24
   5.1.5 Digest Subtype ....................................   26
   5.1.6 Parallel Subtype ..................................   27
   5.1.7 Other Multipart Subtypes ..........................   28
   5.2 Message Media Type ..................................   28
   5.2.1 RFC 822 Subtype ....................................   28
   5.2.2 Partial Subtype ...................................   29
   5.2.2.1 Message Fragmentation and Reassembly ............   30
   5.2.2.2 Fragmentation and Reassembly Example ............   31
   5.2.3 External-Body Subtype .............................   33
   5.2.4 Other Message Subtypes ............................   40
   6. Experimental Media Type Values .......................   40
   7. Summary ..............................................   41
   8. Security Considerations ..............................   41
   9. Authors' Addresses ...................................   42



Freed & Borenstein          Standards Track