World Library  
Flag as Inappropriate
Email this Article

HZ (character encoding)

Article Id: WHEBN0002845127
Reproduction Date:

Title: HZ (character encoding)  
Author: World Heritage Encyclopedia
Language: English
Subject: GB 2312, Extended Unix Code, HZ, Chinese character encoding, Character sets
Collection: Character Sets, Chinese-Language Computing, Encodings of Asian Languages
Publisher: World Heritage Encyclopedia
Publication
Date:
 

HZ (character encoding)

The HZ character encoding is an encoding of GB2312 that was formerly commonly used in email and USENET postings. It was designed in 1989 by Fung Fung Lee (Chinese: 李楓峰) of Stanford University, and subsequently codified in 1995 into RFC 1843.

The HZ, short for Hanzi (simplified Chinese: 汉字; traditional Chinese: 漢字; literally: "Chinese Characters"), encoding was invented to facilitate the use of Chinese characters through e-mail, which at that time only allowed 7-bit characters. Therefore, in lieu of standard ISO 2022 escape sequences (as in the case of ISO-2022-JP) or 8-bit characters (as in the case of EUC), the HZ code uses only printable, 7-bit characters to represent Chinese characters.

It was also popular in USENET networks, which in the late 1980s and early 1990s, generally did not allow transmission of 8-bit characters or escape characters.

Contents

  • Structure and use 1
  • HZ decoders 2
  • Disadvantages 3
  • References 4

Structure and use

In the HZ encoding system, the character sequences "~{" and "~}" act as escape sequences; anything between them is interpreted as Chinese encoded in GB2312 (the most significant bits are ignored). Outside the escape sequences, characters are assumed to be ASCII.

An example will help illustrate the relationship between GB2312, EUC-CN, and the HZ code:

Various forms of the GB2312 code (0xD2BB) for the character "一" (one)
Form Code With escape sequences Remarks
Kuten / Qūwèi / 区位 form 5027 Zone (ku/qū/) 50, point (ten/wèi/) 27
ISO 2022 form 5216 3B16 0E16 5216 3B16 0F16 50 + 32 = 82 = 5216
EUC-CN form D216 BB16 D216 BB16 5216 ∨ 8016 = D216
HZ form (standard) 5216 3B16 7E16 7B16 5216 3B16 7E16 7D16 Appears as ~{R;~} without HZ decoder
HZ form (alternate) D216 BB16 7E16 7B16 D216 BB16 7E16 7D16 EUC form acceptable to at least some decoders

HZ was originally designed to be used purely as a 7-bit code. However, when situations allow, the escape sequences "~{" and "~}" sometimes surround characters represented in EUC-CN; this alternative use allows Chinese to be readable either with the help of HZ decoder software, or with a system that understands EUC-CN.

Additionally, the specification defines that

  • the sequence "~~" is to be treated as encoding a single ASCII "~"
  • the character "~" followed by a newline is to be discarded.

However, not all HZ decoders follow these two rules.

HZ decoders

The first HZ decoder was written in 1989 by the code's inventor for the Unix operating system.

The hztty program, also for the Unix operating system, was also among the first and one of the most popular HZ decoders. It deviates from the specification in that it will display the escape sequences (i.e., "~{" and "~}"), and it does not treat "~~" and "~" followed by a newline specially. This was probably to allow software which assumes one character to occupy one screen position (on a text screen) to function correctly without modification.

Support on Microsoft Windows came later, and a number of third-party "Chinese systems" support HZ. These systems may provide an option to hide the escape sequences.

Disadvantages

Because of its escape sequences, and furthermore because its escape delimiters are printable characters in ASCII, it is fairly easy to construct attack byte sequences that round-trip from HZ to Unicode and back. Use of HZ encoding is thus treated as suspicious by malware protection suites.[1]

References

  1. ^ http://bugzilla.mozilla.org/show_bug.cgi?id=935453
  • RFC 1843
  • HZ — A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and ASCII Characters, Archived version
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.