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MIME (Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies (RFC1521)

IP.com Disclosure Number: IPCOM000002352D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2001-Nov-09

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

N. Borenstein: AUTHOR [+2]

Abstract

STD 11, RFC 822 defines a message representation protocol which specifies considerable detail about message headers, but which leaves the message content, or message body, as flat ASCII text. This document redefines the format of message bodies to allow multi-part textual and non-textual message bodies to be represented and exchanged without loss of information. This is based on earlier work documented in RFC 934 and STD 11, RFC 1049, but extends and revises that work. Because RFC 822 said so little about message bodies, this document is largely orthogonal to (rather than a revision of) RFC 822.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 2% of the total text.

Network Working Group                                      N. Borenstein

Request for Comments: 1521                                      Bellcore

Obsoletes: 1341                                                 N. Freed

Category: Standards Track                                       Innosoft

                                                          September 1993

         MIME (Multipurpose Internet Mail Extensions) Part One:

                Mechanisms for Specifying and Describing

                 the Format of Internet Message Bodies

Status of this Memo

   This RFC 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" for the standardization state and status

   of this protocol.  Distribution of this memo is unlimited.

Abstract

   STD 11, RFC 822 defines a message representation protocol which

   specifies considerable detail about message headers, but which leaves

   the message content, or message body, as flat ASCII text.  This

   document redefines the format of message bodies to allow multi-part

   textual and non-textual message bodies to be represented and

   exchanged without loss of information.  This is based on earlier work

   documented in RFC 934 and STD 11, RFC 1049, but extends and revises

   that work.  Because RFC 822 said so little about message bodies, this

   document is largely orthogonal to (rather than a revision of) RFC

   822.

   In particular, this document is designed to provide facilities to

   include multiple objects in a single message, to represent body text

   in character sets other than US-ASCII, to represent formatted multi-

   font text messages, to represent non-textual material such as images

   and audio fragments, and generally to facilitate later extensions

   defining new types of Internet mail for use by cooperating mail

   agents.

   This document does NOT extend Internet mail header fields to permit

   anything other than US-ASCII text data.  Such extensions are the

   subject of a companion document [RFC-1522].

   This document is a revision of RFC 1341.  Significant differences

   from RFC 1341 are summarized in Appendix H.

Borenstein & Freed                                              [Page 1]

RFC 1521                          MIME                    September 1993

Table of Contents

   1.     Introduction.......................................  3

   2.     Notations, Conventions, and Generic BNF Grammar....  6

   3.     The MIME-Version Header Field......................  7

   4.     The Content-Type Header Field......................  9

   5.     The Content-Transfer-Encoding Header Field......... 13

   5.1.   Quoted-Printable Content-Transfer-Encoding......... 18

   5.2.   Base64 Content-Transfer-Encoding................... 21

   6.     Additional Content-Header Fields................... 23

   6.1.   Optional Content-ID Header Field................... 23

   6.2.   Optional Content-Description Header Field.......... 24

   7.     The Predefined Content-Type Values................. 24

   7.1.   The Text Content-Type.............................. 24

   7.1.1. The charset parameter.............................. 25

   7.1.2. The Text/plain subtype............................. 28

   7.2.   The Multipart Content-Type......................... 28

   7.2.1. Multipart:  The common syntax...................... 29

   7.2.2. The Multipart/mixed (primary) subty...