Japanese Character Encoding for Internet Messages (RFC1468)
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
J. Murai: AUTHOR [+3]
This document describes the encoding used in electronic mail [RFC822] and network news [RFC1036] messages in several Japanese networks. It was first specified by and used in JUNET [JUNET]. The encoding is now also widely used in Japanese IP communities.
Network Working Group J. Murai
Request for Comments: 1468 Keio University
E. van der Poel
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. Distribution of this memo is
This document describes the encoding used in electronic mail [RFC822]
and network news [RFC1036] messages in several Japanese networks. It
was first specified by and used in JUNET [JUNET]. The encoding is now
also widely used in Japanese IP communities.
The name given to this encoding is "ISO-2022-JP", which is intended
to be used in the "charset" parameter field of MIME headers (see
[MIME1] and [MIME2]).
The text starts in ASCII [ASCII], and switches to Japanese characters
through an escape sequence. For example, the escape sequence ESC $ B
(three bytes, hexadecimal values: 1B 24 42) indicates that the bytes
following this escape sequence are Japanese characters, which are
encoded in two bytes each. To switch back to ASCII, the escape
sequence ESC ( B is used.
The following table gives the escape sequences and the character sets
used in ISO-2022-JP messages. The ISOREG number is the registration
number in ISO's registry [ISOREG].
Esc Seq Character Set ISOREG
ESC ( B ASCII 6
ESC ( J JIS X 0201-1976 ("Roman" set) 14
ESC $ @ JIS X 0208-1978 42
ESC $ B JIS X 0208-1983 87
Note that JIS X 0208 was called JIS C 6226 until the name was changed
on March 1st, 1987. Likewise, JIS C 6220 was renamed JIS X 0201.
The "Roman" character set of JIS X 0201 [JISX0201] is identical to
ASCII except for backslash () and tilde (~). The backslash is
replaced by the Yen sign, and the tilde is replaced by overline. This
set is Japan's national variant of ISO 646 [ISO646].
The JIS X 0208 [JISX0208] character sets consist of Kanji, Hiragana,
Katakana and some other symbols and characters. Each character takes
up two bytes.
For further details about the JIS Japanese national character set
standards, refer to [JISX0201] and [JISX0208]. For further
information about the escape sequences, see [ISO2022] and [ISOREG].
If there are JIS X 0208 characters on a line, there must be a switch
to ASCII or to the "Roman" set of JIS X 0201 before the end of the
line (i.e., before the CRLF). This means that the next line starts in
the character set that was switched to before the end of the previous
Also, the text must ...