Network Working Group Y. Wei
Request for Comments: 1842 AsiaInfo Services Inc.
Category: Informational Y. Zhang
 Harvard Univ.
 J. Li
 Rice Univ.
 J. Ding
 AsiaInfo Services Inc.
 Y. Jiang
 Univ. of Maryland
 August 1995
 ASCII Printable Characters-Based Chinese Character Encoding
 for Internet Messages
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.
Abstract
 This document describes the encoding used in electronic mail [RFC822]
 and network news [RFC1036] messages over the Internet. The 7-bit
 representation of GB 2312 Chinese text was specified by Fung Fung Lee
 of Stanford University [Lee89] and implemented in various software
 packages under different platforms (see appendix for a partial list
 of the available software packages that support this encoding
 method). It is further tested and used in the usenet newsgroups
 alt.chinese.text and chinese.* as well as various other network
 forums with considerable success. Future extensions of this encoding
 method can accommodate additional GB character sets and other east
 asian language character sets [Wei94].
 The name given to this encoding is "HZ-GB-2312", which is intended to
 be used in the "charset" parameter field of MIME headers (see [MIME1]
 and [MIME2]).
Table of Contents
 1. Introduction................................................ 2
 2. Description................................................. 3
 3. Formal Syntax............................................... 4
 4. MIME Considerations......................................... 5
 5. Background Information...................................... 5
 6. References.................................................. 6
 7. Acknowledgements............................................ 6
 8. Security Considerations..................................... 7
 9. Authors' Addresses.......................................... 7
 10. Appendix: List of Software Implementing HZ Representation... 9
1. Introduction
 Chinese (and other east Asia languages) characters are encoded with
 multiple bytes to guarantee sufficient coding space for the large
 number of glyphs these languages contain. With the prolification of
 internetwork traffic around the world, it becomes necessary to define
 ways to facilitate the transfer of text in multiple-byte character-
 set languages (hereafter as Chinese text) over internet.
 There are two layers of concerns need to be addressed by any
 mechanism whose purpose is to transfer Chinese text over internet.
 The first is on application layer, in which concerned applications
 should be able to recognize the encoding of the text and/or discern
 different character sets which might be mixed in the text and handle
 it accordingly. The second layer is the actual transport of Chinese
 text between point A to point B over the Internet. Because the
 prevailing mail transport protocol used over internet, the Simple
 Mail Transport Protocol (aka. SMTP) was designed originally for ASCII
 character set only, many internet mail agents are not 8 bit clean and
 therefore introduce challenges for any attempt to actually implement
 a mechanism for the transport of Chinese text over internet.
 Here we describe a mechanism for transmission of Chinese text over IP
 network. This described mechanism has being implemented by various
 software package dealing with multi-language support and has been
 tested on USENET newsgroups and other types of internet forums over
 the last two years. The test results shows that the HZ representation
 can pass through almost all existing mail delivery agents without
 being corrupted. The HZ representation currently handles GB2312-80
 Chinese character set only. Further expansion to other Chinese
 encoding systems and to other East Asia Language is under
 consideration.
2. Description
 For an arbitrary mixed text with both Chinese coded text strings and
 ASCII text strings, we designate to two distinguishable text modes,
 ASCII mode and HZ mode, as the only two states allowed in the text.
 At any given time, the text is in either one of these two modes or in
 the transition from one to the other. In the HZ mode, only printable
 ASCII characters (0x21-0x7E) are meanful with the size of basic text
 unit being two bytes long.
 In the ASCII mode, the size of basic text unit is one (1) byte with
 the exception '~~', which is the special sequence representing the
 ASCII character '~'. In both ASCII mode and HZ mode, '~' leads an
 escape sequence. However, as HZ mode has basic size of text unit
 being 2 bytes long, only the '~' character which appears at the first
 byte of the the two-byte character frame are considered as the start
 of an escape sequence.
 The default mode is ASCII mode. Each line of text starts with the
 default ASCII mode. Therefore, all Chinese character strings are to
 be enclosed with '~{' and '~}' pair in the same text line.
 The escape sequences defined are as the following:
 ~{ ---- escape from ASCII mode to GB2312 HZ mode
 ~} ---- escape from HZ mode to ASCII mode
 ~~ ---- ASCII character '~' in ASCII mode
 ~\n ---- line continuation in ASCII mode
 ~[!-z|] ---- reserved for future HZ mode character sets
 A few examples of the 7 bit representation of Chinese GB coded test
 taken directly from [Lee89] are listed as the following:
 Example 1: (Suppose there is no line size limit.)
 This sentence is in ASCII.
 The next sentence is in GB.~{<:Ky2;S{#,NpJ)l6HK!#~}Bye.
 Example 2: (Suppose the maximum line size is 42.)
 This sentence is in ASCII.
 The next sentence is in GB.~{<:Ky2;S{#,~}~
 ~{NpJ)l6HK!#~}Bye.
 Example 3: (Suppose a new line is started for every mode switch.)
 This sentence is in ASCII.
 The next sentence is in GB.~
 ~{<:Ky2;S{#,NpJ)l6HK!#~}~
 Bye.
3. Formal Syntax
 The notational conventions used here are identical to those used in
 RFC 822 [RFC822].
 The * (asterisk) convention is as follows:
 l*m something
 meaning at least l and at most m somethings, with l and m taking
 default values of 0 and infinity, respectively.
 message = headers 1*( CRLF *single-byte-char *segment
 single-byte-seq *single-byte-char )
 ; see also [MIME1] "body-part"
 ; note: must end in ASCII
 headers = <see [RFC822] "fields" and [MIME1] "body-part">
 segment = single-byte-segment / double-byte-segment
 single-byte-segment = 1*single-byte-char
 double-byte-segment = double-byte-seq 1*( one-of-94 one-of-94 )
 single-byte-seq = "~}"
 double-byte-seq = "~{"
 CRLF = CR LF
 ; ( Octal, Decimal.)
 CR = <ASCII CR, carriage return>; ( 15, 13.)
 LF = <ASCII LF, linefeed> ; ( 12, 10.)
 one-of-94 = <any one of 94 values> ; (41-176, 33.-126.)
 single-byte-char = <any 7BIT, including bare CR & bare LF, but NOT
 including CRLF, not including > / "~~">;
 7BIT = <any 7-bit value> ; ( 0-177, 0.-127.)
4. MIME Considerations
 The name given to the HZ character encoding is "HZ-GB-2312". This
 name is intended to be used in MIME messages as follows:
 Content-Type: text/plain; charset=HZ-GB-2312
 The HZ-GB-2312 encoding is already in 7-bit form, so it is not
 necessary to use a Content-Transfer-Encoding header.
5. Background Information
 A GB code is a two byte character withe the first byte is in the
 range of 0x21-0x77 and the second byte in the range 0x21-0x7E. As the
 printable ASCII subset of characters are single byte character in the
 range of 0x21--0x7E, two printable ASCII characters can represent a
 two byte GB coded Chinese character if proper escape sequence is used
 to indicate the proper text mode. This form the base of the above
 described HZ 7-bit representation methods. Further, with the use of a
 printable ASCII character, '~', as the leading byte of the escape
 sequence, the HZ representation eliminated the need of reserving any
 non-printable ASCII characters, which are commonly used by
 application programs (as well as system environment) for various
 control function or other special signaling. Therefore, the HZ
 representation method described here posses the least probability of
 interfering with the host and network environment. This is also a
 convenient for application for implementing the HZ coding method.
 HZ representation method has been implemented in various Chinese
 software across computer hardware platforms. It has also being tested
 for more than two years over USENET newsgroups, alt.chinese.text and
 chinese.*, for the transmission of Chinese texts over the internet.
 The original points of those transferred Chinese texts are
 geographically scattered around the world and under the constraints
 of vast different system and network environments. Therefore, such a
 test group may well represent a rather complete sample of the real
 internet world. The successful test of the HZ representation method
 therefore builds up the confidence that it is well suited for
 transmitting multi-byte text messages over the internet.
 Under HZ representation, ASCII text remain as 7-bit characters and
 therefore HZ representation together with the 7-bit ASCII character
 set can be viewed as forming a superset of characters.
6. References
 [ASCII] American National Standards Institute, "Coded character set
 -- 7-bit American national standard code for information
 interchange", ANSI X3.4-1986.
 [GB 2312] Technical Administrative Bureau of P.R.China, "Coding of
 Chinese Ideogram Set for Information Interchange Basic Set",
 GB 2312-80.
 [Lee89] Lee, F., "HZ - A Data Format for Exchanging Files of
 Arbitrarily Mixed Chinese and ASCII characters", RFC 1843,
 Stanford University, August 1995.
 [MIME1] Borenstein N., and N. Freed, "MIME (Multipurpose Internet
 Mail Extensions) Part One: Mechanisms for Specifying and Describing
 the Format of Internet Message Bodies", RFC 1521, Bellcore, Innosoft,
 September 1993.
 [MIME2] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
 Part Two: Message Header Extensions for Non-ASCII Text", RFC 1522,
 University of Tennessee, September 1993.
 [RFC822] Crocker, D., "Standard for the Format of ARPA Internet
 Text Messages", STD 11, RFC 822, UDEL, August 1982.
 [RFC1036] Horton M., and R. Adams, "Standard for Interchange of
 USENET Messages", RFC 1036, AT&T Bell Laboratories, Center for
 Seismic Studies, December 1987.
 [Wei94] Wei, Yagui, "A Proposal for a Consolidated Collection of
 East Asian Language Coding Standards Using Solely ASCII Printable
 Characters", June 30, 1994.
7. Acknowledgements
 Many people have involved the design and specification of the HZ 7-
 bit Chinese representation system at different stages. Most notable
 among them are Ed Lai, Chunqing Cheng, Fung Fung Lee, and Ricky
 Yeung. This document is merely a recollection of thoughts and efforts
 made collectively by this group of people whose devotion has led to
 the current success of the HZ Chinese representation over the
 Internet. Further, the authors wish to thank AsiaInfo Services Inc.
 for sponsoring the preparation of this document and for facilitate
 the communication need to refine this document.
8. Security Considerations
 Security issues are not discussed in this memo.
9. Authors' Addresses
 Ya-Gui Wei
 AsiaInfo Services Inc.
 One Galleria Tower
 13355 Noel Rd. Suite 1340
 Dallas, TX 75240
 Phone: (214) 788-4141
 Fax: (214) 788-0729
 EMail: HZRFC@usai.asiainfo.com
 Yun Fei Zhang
 CfA
 Harvard University
 MS 66
 60 Garden St.
 Cambridge, MA 02138
 Phone: (617)-860-9444
 EMail: zhang@orion.harvard.edu
 Jian Q. Li
 Rice University
 ONS - MS 119
 P.O. Box 1892
 Houston, Texas 77251-1892
 Phone: (713)285-5328
 EMail: jian@is.rice.edu
 Jian Ding
 ISTIC Bldg, Room 431
 15 Fuxing Road,
 Beijing, China 100038
 Phone: 86 10 853-7120
 Fax: 86 10 853-7123
 EMail: ding@Beijing.AsiaInfo.com
 Yuan Jiang
 Electrical Engineering Department
 University of Maryland
 College Park, MD 200742
 Phone: 301-405-3729
 EMail: yjj@eng.umd.edu
10. Appendix: List of Software Implementing HZ Representation
 In the following, we compiled a list on software packages support the
 HZ Chinese representation method. Though this list is far from
 complete, it is visible that support for HZ representation has be
 implemented for major hardware and software platforms. For more
 information on the listed software packages (and for other
 information pertain to Chinese computing), please refer to the
 internet site: ftp://ftp.ifcss.org/pub/software/ or its mirrors at
 the following sites:
 at Beijing, China: ftp://info.bta.net.cn:/pub/software/;
 at Shanghai, China: ftp://info.bta.net.cn:/pub/software/;
 at Taiwan: ftp://nctuccca.edu.tw/pub/Chinese/ifcss/;
 or ftp://ftp.edu.tw:/Chinese/ifcss/software/;
 At Singapore: ftp://ftp.technet.sg:/pub/chinese/;
 at California, U.S.A.: ftp://cnd.org/pub/software/.
 The software in the next section are listed by its name and followed
 by the current version number, release date (in parenthesis) and the
 author(s) of the software. A brief description of the functionality
 of the software starts at the line immediately after the headline and
 lead by character string "--". Two consecutive packages are separated
 by a blank line.
 zwdos (V2.2, March 5, 1993) by Wei Ya-Gui
 -- MS-DOS kernal extension that gives DOS text mode programs the
 ability to enter, display, manipulate and print 'zW' and HZ
 Chinese text. Small memory requirement. Supports EGA,
 VGA or Hercules Monographic displays.
 HZ (V2.0, Feb. 7, 1995) by Fung F. Lee
 -- Conversion from HZ to GB, GB to HZ, and zW to HZ respectively.
 Versions for PC, Mac and Unix exist.
 XingXing (V4.2, Mar 29. 1995) by Wang Xiangdong
 -- chinese word processor for PC.
 NJStar (V3.00, Feb. 10, 1994 by Hongbo Ni)
 -- GB Word Processor (Viewer, editor, printing, converter)
 Supports EGA/(mono)VGA/SuperVGA monitors, and various
 printers, Chinese<->English dictionary lookup, HanziInfo
 and glossary; Includes more than 20 Chinese input methods
 with Intelligent LianXiang and fuzzy Pinyin; Speed up with
 sentence based Pinyin; Reads and writes GB,Hz,zW & Big5 files;
 DOS Shell; Configurable.
 QuickStar (V3.0, June 7, 1995) by Anthony Mai
 -- Compact size Chinese edit software for PC. PinYin, CiZu,
 WuBi, GuoBiao, ASCII etc input method. Translate to/from GB,
 HZ and Big5 coded Chinese files.
 cnprint (V2.6, Jan. 25, 95) by Yidao Cai
 -- print GB/Hz/BIG5/JIS/KSC/UTF8 etc or convert to PostScript
 (conforms to EPSF-3.0). Both DOS and UNIX version available.
 dm24 (V2.0, Sept. 1993) by Gongquan Chen)
 -- Chinese GB/HZ printing program for EPSON 24pin printer
 HXLASER (V2.6, Feb. 1994) by Chen, Gongquan
 -- A GB/HZ/BIG5 file printing program for HP LaserJet plus and
 later model printers.
 CNVIEW (V3.0, Jan. 1, 1995) by Jifang Lin
 -- View GB/Hz/Big5 encoded Chinese text file on IBM-PC
 & compatibles
 ZWLIST (V1.1, Nov. 24, 1993) by Gongquan Chen
 -- Chinese HZ/GB/BIG5 File Browser for ZWDOS
 zwTool (V1.0, Oct. 30,1993) by Gongquan Chen
 -- a MSDOS TSR program for input of Chinese characters in text
 mode; Developed primarily for Chinese programmers using IDE
 (Integrated Development Environment, like Borland's Turbo
 languages); Supports GB/HZ; EGA/VGA required;
 DateStar (V1.1) by Youzhen Cheng
 -- Chinese Calendar Producer. Displays Chinese and western
 calendar in ASCII code, BIG-5 code, GuoBiao code (PRC
 Standard), and HZ code (Network)
 MacViewHZ (V2.21 Dec. 93) by Xiaodong Chen
 -- Display and print GB/HZ or BIG5 coded Chinese text files on
 Macintosh without Chinese OS system, with easy to use Mac
 user interface including multiple windows and simple editing
 features such as delete, copy, cut and paste.
 MacHZTerm (V0.52) by Xin Xu
 -- a communication program using CommToolBox, capable of
 displaying GB, HZ, Big5 texts on line. No Chinese OS required.
 System 7 recommended.
 HanziTerm (V0.5) by Ricky Yeung
 -- A terminal emulator for Mac Chinese OS 6.0.x or later.
 Support 8-bit character code, HZ, and zW.
 Tex-Edit-HZ (V1.0, Dec. 18 1993) by Tom Bender and Tie Zeng.
 -- A MAC WorldScript savvy Text editor with HZ<->GB conversion
 feature.
 MacBlue Telnet (V2.6.6, Feb 16, 1995) by MacBlue
 -- A Telnet program that can handle all Chinese encodings
 (such as HZ, GB, Big5, ET etc), EUC-JIS and EUC-KSC; based on
 NCSA Telnet with built-in hanzi input methods.
 rnMac (V1.3b5) by Roy Wood
 -- Offline Newsreader including GB <-> HZ conversion
 Weiqi267 (V2.67) by Xiangbo Kang
 -- record Weiqi games and transfer them through net.
 GB, HZ 100 % compatible (but Russian char disabled).
 There is a user guide in HZ coding.
 * Now can also be used for Chinese Chess.
 TwinBridge (V3.2, Nov. 16, 1994) by Twinbridge Software Corporation
 -- an interface between Windows and applications, it allows
 Chinese character processing in Windows applications like
 Word for Windows, Ami Pro, Excel, etc.
 You can edit Chinese characters like English characters
 in most of applications.
 WinHZ (V1.1, April 13, 1995) by Tian Bogang
 -- HZ extension for Chinese systems for Windows
 HZcomm (V1.5, Nov. 14, 1993) by Nick Ke Ning.
 -- HZ coding supported communication program under Chinese
 Windows System (GB internal coded). Good for reading/writing
 HZ coded E-mail and news(alt.chinese.text) on line in
 Windows 3.1 for PCs.
 SimpTerm (V0.8.0) by Jianqing Hu
 -- A Chinese communication program for MS-Windows 3.1
 with build in support for BIG5, HZ and GB encoded text.
 ChPad (V1.31) by Tian Bogang
 -- GUO BIAO and HZ file browser for MS WINDOWS 3.1
 SilkRoad (V1.0) by Antony C. Hu
 -- GB/HZ Viewer for MS-Windows 3.1
 gnus-chinese (V1.0, Apr. 26 1994) by Ning Mosberger-Tang
 -- convert HZ articles to the code understandable by your
 terminal automatically in GNUS newsreader (for GNU EMACS).
 requires conversion program (e.g. hz2gb and gb2hz) to do the
 actual conversion.
 irchat (V2.4jp4cn0) by HIROSE Tutomu
 -- irc client e-lisp program on Mule
 patched to handle HZ and Big5
 now we can read/write all JIS/HZ/Big5 simultaneously on irc
 hztty (V2.0 Jan 29, 1994) by Yongguang Zhang
 -- This program turns a tty session from one encoding to another.
 For example, running hztty on cxterm can allow you to
 read/write Chinese in HZ format.
 BeTTY/CCF/B5Encode package (V1.534, 1995年03月22日) by Jing-Shin Chang
 -- a chinese code conversion package for codes widely used
 in Taiwan and the GB code widely used in Mainland, plus
 a 7-bit Big5 encoding method (B5Encode3/B5E3, an extension
 to HZ encoding for GB),
 including off-line converters (CCF/Chinese Code Filters and
 B5E/B5Encode) and an on-line converter (BeTTY) which simulates
 your native chinese terminal to become aware of the coding
 systems widely used in Taiwan and GB, HZ encoding.
 gb2jis & jis2gb (V1.5, 1995年5月11日) by Koichi Yasuoka
 -- convert GB (or HZ) to/from JIS with two-letter pinyin
 gb2ps (V2.02) by Wei SUN
 -- convert GB/HZ to postscript, supports simple page formatting
 (change chinese fonts and font size, cover page, page
 number, etc). Five chinese fonts are provided in this
 release, they are Song, Kai, Fang Song, Hei and FanTi
 The HZ ENCODING is also supported.
 ChiRK (V1.2a) by Bo Yang
 -- GB/HZ/BIG5 text viewer on terminals (or emulations) capable
 of displaying Tektronics 401x graphics, such as GraphOn,DEC
 VT240/330, Xterm, Tektool on Sun, EM4105 on PC,
 VersaTerm-Pro on Mac, etc.
 Multi-Localization Enhancement of NCSA Mosaic X 2.4 (V2.4.0)
 by TAKADA, Toshihiro
 -- a patch to make use of various nat'l character sets in NCSA
 Mosaic for X 2.4. You can switch between char-sets in one
 Mosaic. Support ISO 8859-X, KOI-8, GB, HZ, BIG5, KSC & JIS.