RFC 1641 (rfc1641) - Page 1 of 6

Using Unicode with MIME

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