2152: UTF-7 A Mail-Safe Transformation Format of Unicode.

The Unicode Standard, version 2.0, and ISO/IEC 10646-1:1993(E) (as amended) jointly define a 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 2045 through 2049) 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.