Charset name: CP50220

Charset aliases: csCP50220

Suitability for use in MIME text:

Yes, CP50220 is suitable for use with subtypes of the "text"
Content-Type.

Since the CP50220 charset is 7bit, encodings are normally not needed,
even on limited transports.

Published specification(s):

CP50220 is a character encoding in the ISO/IEC 2022 family of
character encodings. It incorporates four different coded character
sets (CCSes), and uses escape sequences to control which one is in
effect. The coded character sets and the escape sequences that
select them are:

US-ASCII ESC ( B
JIS X 0201-Roman ESC ( J
JIS X 0208-1978 ESC $ @
JIS X 0208-1983 ESC $ B

The use of these sequences is subject to the following rules:

(1) US-ASCII is the default CCS at the start of a block of text.
(2) Each line MUST return the CCS setting to US-ASCII at the end.
(3) This charset does not include JIS X 0201-Katakana (half-width
Katakana). So instead of sending those characters, most
applications send full-width Katakana (JIS X 0208). It is highly
recommended to follow this practice.
(4) The character set of CP50220 is based on Windows Codepage 932.
http://msdn.microsoft.com/en-us/goglobal/cc305152.aspx
The conversion between CP50220 and CP932 is the same as the
conversion between ISO-2022-JP and Shift-JIS described on
p. 582 of CJKV Information Processing, Second Edition.

ISO 10646 equivalency table:

The ISO 10646 equivalence of each character can be obtained by first
converting to Windows Codepage 932 and then using one of the
following tables:
http://msdn.microsoft.com/en-us/goglobal/cc305152.aspx
http://unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP932.TXT

http://icu-project.org/repos/icu/data/trunk/charset/data/ucm/windows-932-2000.ucm

Additional information:

CP50220 is a variant of ISO-2022-JP in the same sense as Windows-31J
is a variant of Shift_JIS.
CP50220 is different from ISO-2022-JP in that:
* CP50220 supports the additional characters available in Windows
Codepage 932 (NEC special characters and NEC selection of IBM
extensions)
* The Unicode mapping of some characters is different. See
http://www.w3.org/Submission/japanese-xml/#ambiguity_of_yen
http://www2d.biglobe.ne.jp/~msyk/charcode/cp932/uni2sjis.html

Typical users of CP50220 are web browsers. When a web browser loads
a page which is declared or auto-detected as "ISO-2022-JP", it does
not interpret strictly it as ISO-2022-JP as it is registered in the
IANA Character Sets Registry but as CP50220. When a web browser
posts form data as "ISO-2022-JP", the data is also encoded as
CP50220. Note that although csISO2022JP is an alias of ISO-2022-JP
in the IANA Charset Registry, on Windows it means neither
ISO-2022-JP as registered nor CP50220, but CP50221.
See http://wiki.whatwg.org/wiki/Web_Encodings

An application which decodes CP50220 may accept JIS X 0201-Katakana
encoded with the escape sequence "ESC ( I", with SI/SO, or with raw
8-bit bytes.

The name "CP50220" is in use in the following applications:
* Citrus iconv (used in NetBSD and DragonFly)
* Mojikan http://www.mirai-ii.co.jp/moji/mojikan/
* nkf 2.0.5
* Encode-EUCJPMS-0.06

Moreover, applications which use MLang.DLL or .NET Framework for
converting "ISO-2022-JP" implicitly use this charset.

The reason why the name is not "Windows-50220" is that some
applications which accept the name "CP50220" do not support the
name "Windows-50220".

CP50220 is for use in communicating with legacy systems.
UTF-8 is preferred to CP50220 for new systems.

Related references are:

"Remarks" of "GetEncodings Method" of "System.Text"

http://msdn.microsoft.com/en-us/library/system.text.encoding.getencodings.aspx

"Introduction to JIS X0213 Implementation based on Unicode -
A new Japanese Language Processing Environment for Information
Systems",
Nikkei BP Soft Press, ISBN 978-4891006082, 2008, pp. 17-18, 20,
120-158 (in Japanese)

CP50220 - Legacy Encoding Project
http://legacy-encoding.sourceforge.jp/wiki/index.php?cp50220

Ken Lunde, "CJKV Information Processing, Second Edition"
O'Reilly Media, ISBN 978-0-596-51447-1

Masayuki Moriyama, "Windows-31J Information"
http://www2d.biglobe.ne.jp/~msyk/charcode/cp932/index.html

XML Japanese Profile (Second Edition)
http://www.w3.org/Submission/japanese-xml/

This charset is also known as Windows Codepage 50220.

Person & email address to contact for further information:

NARUSE, Yui
Email: naruse&airemix.jp

Intended usage: LIMITED USE