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Uhhyung Choi
Korea Network Information Center
Network Working Group Kilnam Chon
Internet Draft Hyun Je Park
Uhhyung Choi
July 22, 1993
Korean Character Encoding for Internet Messages
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts.
Internet Drafts are draft documents valid for a maximum of six
months. Internet Drafts may be updated, replaced, or obsoleted by
other documents at any time. It is not appropriate to use Internet
Drafts as reference material or to cite them other than as a "working
draft" or "work in progress."
Please check the 1id-abstracts.txt listing contained in the
internet-drafts Shadow Directories on nic.ddn.mil, nnsc.nsf.net,
nic.nordu.net, ftp.nisc.sri.com, or munnari.oz.au to learn the
current status of any Internet Draft.
This draft document will be submitted to the RFC editor as an
informational document. This document will expire before 2nd March
1993. Distribution of this memo is unlimited. Comments are
solicited and should be sent to ietf-822@dimacs.rutgers.edu.
Introduction
This document describes the encoding method being used to represent
the Hangul, Korean character, in both header and body part of the
internet electronic mail system. This encoding method was specified
in System Development Network (SDN) in 1991, and has since then been
used, it has widely spread from SDN to other Korean IP networks.
This document describes the name and encoding method of Hangul that
are to be used in order to match the message body format of MIME
[MIME] and the RFC1342 [RFC1342] header format.
This document describes only the encoding method for plain text.
Other text subtypes, rich text and similar forms of text, are beyond
the scope of this document.
Chon et al Expires December 10, 1993 [Page 1]
Internet Draft May 11, 1993
Description
It is assumed that the starting code of the message is ASCII. ASCII
and Hangul can be distinguished by use of the shift function. For
example, the code SO will alert us that the up coming bytes will be
either a Hangul character in 2 bytes or an ASCII space character in
a single byte. To return to ASCII the SI code is used.
Therefore, the escape sequence, shift function and character set used
in a Hangul message are as follows:
SO KSC 5601
SI ASCII
ESC $ ) C Appears in the first line of the message
The KSC 5601 [KSC5601] character set that includes Hangul, Chinese
ideographic characters, graphic and foreign characters, etc. is two
bytes long for each character.
For more information about Korean character codes please refer to the
KSC 5601-1989 document. Also, for more detailed information about the
escape sequence and the shift function you can look for the ISO 2022
[ISO2022] document.
Formal Syntax
Where this document in its formal syntax does not agree with the
description part, priority should be given to the formal syntax of
the document.
The notations used in this section of the document are according to
those used in RFC822 [RFC822] with the same meaning.
* (asterisk) has the following meaning :
l*m "anything"
The above means that "anything" has to be used at least l times and
at most m times. Default values for l and m are 0 and infinitive,
respectively.
body = *e-line *1( designator *( e-line / h-line ))
designator = ESC "$" ")" "C"
e-line = *text CRLF
h-line = *text 1*( segment *text ) CRLF
Chon et al Expires December 10, 1993 [Page 2]
Internet Draft May 11, 1993
segment = SO one-of-94 one-of-94
*( *SP 1*(one-of-94 one-of-94)) SI
; ( Octal, Decimal.)
ESC = <ISO 2022 ESC, escape> ; ( 33, 27.)
SO = <ASCII SO, shift out> ; ( 16, 14.)
SI = <ASCII SI, shift in> ; ( 17, 15.)
SP = <ASCII SP, space> ; ( 40, 32.)
one-of-94 = <any char in 94-char set> ; (41-176, 33.-126.)
CHAR = <any ASCII character> ; ( 0-177, 0.-127.)
text = <any CHAR, including bare CR & bare LF, but NOT
including CRLF, and not including ESC, SI, SO>
MIME and RFC1342 Considerations
The name to be used for the Hangul encoding scheme in the contents is
"ISO-2022-KR". This name when used in MIME message form would be:
Content-Type: text/plain; charset=iso-2022-kr
Since the Hangul encoding is done with 7 bit format in nature, the
Content-Transfer-Encoding-header does not need to be used. However,
while using the Hangul encoding, current Hangul message softwares
does not support Base64 or Quoted-Printable encoding applied on
already encoded Hangul messages.
The Hangul encoded in the header part of the message is Korean EUC
[EUC-KR]. In the EUC-KR encoding, the bytes with 8th bit set will
be recognized as KSC-5601 charecters. To use Hangul in the header
part, according to the method proposed in RFC1342, the encoded
Hangul are "B" or "Q" encoded. When doing so, the name to be used
will be EUC-KR.
Background Information
The Hangul encoding system is based on the ISO 2022 [ISO2022]
environment according to its 4/4 announcement. However, the Hangul
encoding does not include the announcement's escape sequence.
Chon et al Expires December 10, 1993 [Page 3]
Internet Draft May 11, 1993
The KSC 5601 used in this document is, in definition, identical to
the KSC 5601-1987, KSC 5601-1989 and KSC 5601-1992's 94x94 octet
definition. Therefore, any revision that refers to KSC-5601 after
1992 is to be considered as having the same meaning.
At present, the Hangul encoding system is based on the experience
acquired from the former widely used "N-Byte Hangul" among UNIX
users. Actually, the encoding method, "N-Byte Hangul", using SO and
SI was the encoding method used in SDN before KSC 5601 was made a
national standard.
This code is intended to be used for the information interchange of
Hangul messages; any other use of the code is not considered apt.
References
[ASCII] American National Standards Institute, "Coded character set
-- 7-bit American national standard code for information
interchange", ANSI X3.4-1968
[ISO2022] International Organization for Standardization (ISO),
"Information processing -- ISO 7-bit and 8-bit coded character sets
-- Code extension techniques", International Standard, 1986,
Ref. No. ISO 2022-1986 (E).
[KSC5601] Korea Industrial Standards Association, "Code for
Information Interchange (Hangul and Hanja)," Korean Industrial
Standard, 1987, Ref. No. KS C 5601-1989.
[EUC-KR] Korea Industrial Standards Association, "Hangul Unix
Environment," Korean Industrial Standard, 1992, Ref. No.
KS C 5861-1992.
[RFC822] David H. Crocker, "Standard for the Format of ARPA Internet
Text Messages", Internet standard, August 1982, RFC822.
[MIME] Nathaniel Borenstein and Ned Freed, "MIME (Multipurpose
Internet Mail Extensions): Mechanisms for Specifying and Describing
the Format of Internet Message Bodies", Proposed Internet standard,
June 1992, RFC1341.
[RFC1342] K. Moore, "Representation of Non-ASCII Text in Internet
Message Headers", Proposed Internet standard, June 1992, RFC1342.
Security Considerations
This document does not include security considerations.
Chon et al Expires December 10, 1993 [Page 4]
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Acknowledgments
The authors wants to thank all the people who assisted in drafting
this document. In particular, we thank Erik von der Poel, Felix M.
Villarreal, Ienup Sung, Kyoung Namgoong, and Kyuho Kim.
Authors' Addresses
Kilnam Chon
Korea Advanced Institute of Science and Technology
Department of Computer Science
Taejon, 305-701, Republic of Korea
Tel: +82-42-869-3514
Fax: +82-42-869-3510
Email: chon@cosmos.kaist.ac.kr
Hyun Je Park
Solvit Chosun Media, Inc.
748-16 Yeoksam-Dong, Kangnam-Gu
Seoul, 135-080, Republic of Korea
Tel: +82-2-561-0361
Fax: +82-2-569-4847
Email: hjpark@dino.media.co.kr
Uhhyung Choi
Korea Advanced Institute of Science and Technology
Department of Computer Science
Taejon, 305-701, Republic of Korea
Tel: +82-42-869-3554
Fax: +82-42-869-3510
Email: uhhyung@kaist.ac.kr
Chon et al Expires December 10, 1993 [Page 5]
--
Uhhyung Choi
Korea Network Information Center