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Network Working Group                                             Y. WeiRequest 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 1995ASCII Printable Characters-Based Chinese Character Encodingfor Internet MessagesStatus 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]).Wei, et al                   Informational                      [Page 1]

RFC 1842            ASCII/Chinese Character Encoding         August 1995Table of Contents1.     Introduction................................................22.     Description.................................................33.     Formal Syntax...............................................44.     MIME Considerations.........................................55.     Background Information......................................56.     References..................................................67.     Acknowledgements............................................68.     Security Considerations.....................................79.     Authors' Addresses..........................................710.    Appendix: List of Software Implementing HZ Representation...91. 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.Wei, et al                   Informational                      [Page 2]

RFC 1842            ASCII/Chinese Character Encoding         August 19952. 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.Wei, et al                   Informational                      [Page 3]

RFC 1842            ASCII/Chinese Character Encoding         August 19953. Formal Syntax   The notational conventions used here are identical to those used inRFC 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.)Wei, et al                   Informational                      [Page 4]

RFC 1842            ASCII/Chinese Character Encoding         August 19954. 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.Wei, et al                   Informational                      [Page 5]

RFC 1842            ASCII/Chinese Character Encoding         August 19956. 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.Wei, et al                   Informational                      [Page 6]

RFC 1842            ASCII/Chinese Character Encoding         August 19958. 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.eduWei, et al                   Informational                      [Page 7]

RFC 1842            ASCII/Chinese Character Encoding         August 1995   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.eduWei, et al                   Informational                      [Page 8]

RFC 1842            ASCII/Chinese Character Encoding         August 199510. 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/;             orftp://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.Wei, et al                   Informational                      [Page 9]

RFC 1842            ASCII/Chinese Character Encoding         August 1995   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.Wei, et al                   Informational                     [Page 10]

RFC 1842            ASCII/Chinese Character Encoding         August 1995   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).Wei, et al                   Informational                     [Page 11]

RFC 1842            ASCII/Chinese Character Encoding         August 1995          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, 1995.03.22) 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, 1995.5.11) 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.Wei, et al                   Informational                     [Page 12]