RFC 1641 (rfc1641) - Page 1 of 6
Using Unicode with MIME
Alternative Format: Original Text Document
Network Working Group D. Goldsmith
Request for Comments: 1641 M. Davis
Category: Experimental Taligent, Inc.
July 1994
Using Unicode with MIME
Status of this Memo
This memo defines an Experimental Protocol for the Internet
community. This memo does not specify an Internet standard of any
kind. Distribution of this memo is unlimited.
Abstract
The Unicode Standard, version 1.1, and ISO/IEC 10646-1:1993(E)
jointly define a 16 bit character set (hereafter referred to as
Unicode) which encompasses most of the world's writing systems.
However, Internet mail (STD 11, RFC 822) currently supports only 7-
bit US ASCII as a character set. MIME (RFC 1521 and RFC 1522) extends
Internet mail to support different media types and character sets,
and thus could support Unicode in mail messages. MIME neither defines
Unicode as a permitted character set nor specifies how it would be
encoded, although it does provide for the registration of additional
character sets over time.
This document specifies the usage of Unicode within MIME.
Motivation
Since Unicode is starting to see widespread commercial adoption,
users will want a way to transmit information in this character set
in mail messages and other Internet media. Since MIME was expressly
designed to allow such extensions and is on the standards track for
the Internet, it is the most appropriate means for encoding Unicode.
RFC 1521 and RFC 1522 do not define Unicode as an allowed character
set, but allow registration of additional character sets.
In addition to allowing use of Unicode within MIME bodies, another
goal is to specify a way of using Unicode that allows text which
consists largely, but not entirely, of US-ASCII characters to be
represented in a way that can be read by mail clients who do not
understand Unicode. This is in keeping with the philosophy of MIME.
Such an encoding is described in another document, "UTF-7: A Mail
Safe Transformation Format of Unicode" [UTF-7].
Goldsmith & Davis