MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text (RFC2047)
Original Publication Date: 1996-Nov-01
Included in the Prior Art Database: 2019-Feb-16
Internet Society Requests For Comment (RFCs)
This particular document is the third document in the series. It describes extensions to RFC 822 to allow non-US-ASCII text data in Internet mail header fields. [STANDARDS-TRACK]
Network Working Group K. Moore Request for Comments: 2047 University of Tennessee Obsoletes: 1521, 1522, 1590 November 1996 Category: Standards Track
MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text
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.
STD 11, RFC 822, defines a message representation protocol specifying considerable detail about US-ASCII message headers, and leaves the message content, or message body, as flat US-ASCII text. This set of documents, collectively called the Multipurpose Internet Mail Extensions, or MIME, redefines the format of messages to allow for
(1) textual message bodies in character sets other than US-ASCII,
(2) an extensible set of different formats for non-textual message bodies,
(3) multi-part message bodies, and
(4) textual header information in character sets other than US-ASCII.
These documents are based on earlier work documented in RFC 934, STD 11, and RFC 1049, but extends and revises them. Because RFC 822 said so little about message bodies, these documents are largely orthogonal to (rather than a revision of) RFC 822.
This particular document is the third document in the series. It describes extensions to RFC 822 to allow non-US-ASCII text data in Internet mail header fields.
Moore Standards Track [Page 1]
RFC 2047 Message Header Extensions November 1996
Other documents in this series include:
+ RFC 2045, which specifies the various headers used to describe the structure of MIME messages.
+ RFC 2046, which defines the general structure of the MIME media typing system and defines an initial set of media types,
+ RFC 2048, which specifies various IANA registration procedures for MIME-related facilities, and
+ RFC 2049, which describes MIME conformance criteria and provides some illustrative examples of MIME message formats, acknowledgements, and the bibliography.
These documents are revisions of RFCs 1521, 1522, and 1590, which themselves were revisions of RFCs 1341 and 1342. An appendix in RFC 2049 describes differences and changes from previous versions.
RFC 2045 describes a mechanism for denoting textual body parts which are coded in various character sets, as well as methods for encoding such body parts as sequences of printable US-ASCII characters. This memo describes similar techniques to allow the encoding of non-ASCII text in various portions of a RFC 822  message header, in a manner which is unlikely to confuse existing message handling software.
Like the encoding techniques described in RFC 2045, the techniques outlined here were designed to allow the use of non-ASCII characters in message headers in a way whic...