Japanese Character Encoding for Internet Messages (RFC2237)
Original Publication Date: 1997-Nov-01
Included in the Prior Art Database: 2019-Feb-15
Internet Society Requests For Comment (RFCs)
This memo defines an encoding scheme for the Japanese Characters, describes "ISO-2022-JP-1", which is used in electronic mail [RFC-822], and network news [RFC 1036]. Also this memo provides a listing of the Japanese Character Set that can be used in this encoding scheme. This memo provides information for the Internet community. It does not specify an Internet standard of any kind.
Network Working Group K. Tamaru Request for Comments: 2237 Microsoft Corporation Category: Informational November 1997
Japanese Character Encoding for Internet Messages
Status of this Memo
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (1997). All Rights Reserved.
This memo defines an encoding scheme for the Japanese Characters, describes "ISO-2022-JP-1", which is used in electronic mail [RFC- 822], and network news [RFC 1036]. Also this memo provides a listing of the Japanese Character Set that can be used in this encoding scheme.
2. Requirements Notation
This document uses terms that appear in capital letters to indicate particular requirements of this specification. Those terms are "MUST", "SHOULD", "MUST NOT", "SHOULD NOT", and "MAY". The meaning of each term are found in [RFC-2119]
RFC 1468 defines the way Japanese Characters are encoded, likewise what this memo defines. It defines the use of JIS X 0208 as the double-byte character set in ISO-2022-JP text.
Today, many operating systems support proprietary extended Japanese characters or JIS X 0212, This includes the Unicode character set, which does not conform to JIS X 0201 nor JIS X 0208. Therefore, this limits the ability to communicate and correspond precise information because of the limited availability of Kanji characters. Fortunately JIS (Japanese Industry Standard) defines JIS X 0212 as "code of the
Tamaru Informational [Page 1]
RFC 2237 Japanese Character Encoding November 1997
supplementary Japanese graphic character set for information interchange". Most Japanese characters which are used in regular electronic mail in most cases can be accommodated in JIS X 0201, JIS X 0208 and JIS X 0212.
Also it is recognized that there is a tendency to use Unicode, however, Unicode is not yet widely used and there is a certain limitation with old electronic mail system. Furthermore, the purpose of this comment is to add the capability of writing out JIS X 0212.
This comment does not describe any representation of iso-2022-jp-1 version information in addition to JIS X 0212 support.
In "ISO-2022-JP-1" text, the initial character code of the message is in ASCII. The "double-byte-seq"(see "Format Syntax" section) (ESC "$" "B" / ESC "$" "@" / ESC "$" "(" "D") is the only designator that indicates that the following character is double-byte, and it is valid until another escape sequence appears. It is very discouraged to use (ESC "$" "@") for double byte character encoding, new implementation SHOULD use only (ESC "$" "B") for double byte encoding instead.
The end of "ISO-2022-JP-1" text MUST be in ASCII. Also it is strongly recommended to back up to the ASCII at the end of each line rather than JIS X 0201-Roman if there is any none ASCII character in middle of a line.
Since "ISO-2022-JP-1" is desig...