RFC 1554 (rfc1554) - Page 1 of 6
ISO-2022-JP-2: Multilingual Extension of ISO-2022-JP
Alternative Format: Original Text Document
Network Working Group M. Ohta
Request for Comments: 1554 Tokyo Institute of Technology
Category: Informational K. Handa
ETL
December 1993
ISO-2022-JP-2: Multilingual Extension of ISO-2022-JP
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Introduction
This memo describes a text encoding scheme: "ISO-2022-JP-2", which is
used experimentally for electronic mail [RFC 822] and network news
[RFC 1036] messages in several Japanese networks. The encoding is a
multilingual extension of "ISO-2022-JP", the existing encoding for
Japanese [2022JP]. The encoding is supported by an Emacs based
multilingual text editor: MULE [MULE].
The name, "ISO-2022-JP-2", is intended to be used in the "charset"
parameter field of MIME headers (see [MIME1] and [MIME2]).
Description
The text with "ISO-2022-JP-2" starts in ASCII [ASCII], and switches
to other character sets of ISO 2022 [ISO2022] through limited
combinations of escape sequences. All the characters are encoded
with 7 bits only.
At the beginning of text, the existence of an announcer sequence:
"ESC 2/0 4/1 ESC 2/0 4/6 ESC 2/0 5/10" is (though omitted) assumed.
Thus, characters of 94 character sets are designated to G0 and
invoked as GL. C1 control characters are represented with 7 bits.
Characters of 96 character sets are designated to G2 and invoked with
SS2 (single shift two, "ESC 4/14" or "ESC N").
For example, the escape sequence "ESC 2/4 2/8 4/3" or "ESC $ ( C"
indicates that the bytes following the escape sequence are Korean KSC
characters, which are encoded in two bytes each. The escape sequence
"ESC 2/14 4/1" or "ESC . A" indicates that ISO 8859-1 is designated
to G2. After the designation, the single shifted sequence "ESC 4/14
4/1" or "ESC N A" is interpreted to represent a character "A with
acute".
Ohta & Handa