oxim-1.2.2.tar.gz_oxim linux

X Window System, Version 11 Input Method Specifications Public Review Draft - November 1990 (Send comments to i18n@expo.lcs.mit.edu) Vania Joloboff Open Software Foundation Bill McMahon Hewlett Packard Company ABSTRACT This chapter addresses the portability and interoperability of programs in different countries. It describes specifications pro- viding to clients of the X Window System Version 11, an interface for input handling of characters in various languages. The specifications make it possible to develop portable applications independent of a particular language or a particular encoding of characters. The specifications are consistent with related specifications from X/Open Portability Guide, Release 3, and ANSI-C. The reader is assumed to be familiar with those, particu- larly with the notion of locale in the C language, therefore they will not be detailed here. Copyright c 1990 by the Massachusetts Institute of Technology. Permission to use, copy, modify, and distribute this documentation for any pur- pose and without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. MIT makes no represen- tations about the suitability for any purpose of the information in this docu- ment. It is provided "as is" without express or implied warranty. This docu- ment is only a draft standard of the MIT X Consortium and is therefore subject to change. 1 XIM Public Review Draft X Window System is a trademark of the Massachusetts Institute of Technology. 2 XIM Public Review Draft 1. Input Method Overview The next paragraphs provide definitions for terms and concepts used in the specification, and a brief overview of the intended use of the abstractions developed for Xlib internationalization. 1.1. What are Input Methods ? A large number of languages in the world rely on an alphabet, a small set of symbols (letters) used to form words. To enter text into a computer in an alphabetic language a user usually has a keyboard on which there exists key symbols corresponding to the alphabet. Sometimes, a few characters of an alphabetic language are missing on the keyboard. Many computer users, who speak a Latin alphabet based language only have a English-based keyboard. They need to hit a combination of keystrokes in order to enter a character that does not exist directly on the keyboard. A number of algorithms have been developed for entering such characters, known as European input methods, or compose input method, or dead-keys input method. In some alphabetic languages, the rendering of characters strings is context sensitive. When entering characters in those languages, a keystroke does not systematically mean appending a new symbol at the end of the string. It may modify the existing strings. Both input and output methods may be used in such languages. With an ideographic writing system, rather than taking a small set of symbols and combining them in different ways to create words, each word consists of one unique symbol (or, occasionally, several symbols). The number of symbols may be very large: 150 000 have been identified in Hanzi, the Chinese ideographic system. There are two major aspects of ideographics system for their computer usage. First, the standard computer character sets in Japan, China, and Korea include roughly 8 000 characters, while sets in Taiwan have between 15 000 and 30 000 characters, which make it necessary to use more than one byte to represent a character. Second, it obviously is impractical to have a keyboard that includes all of a given language's ideographic symbols. Therefore a specific mechanism is required for entering characters so that a keyboard with a reason- able number of keys can be used. Those input methods are usually based on the language's phonetics, but there also exist methods based on the graphics pro- perties of characters. In addition to the ideographic characters, a number of languages often also include a phonetic (alphabetic-based) writing system. The phonetic signs are then engraved on the keyboard and the keystrokes are transformed to their appropriate ideographic counterparts. Here's a brief description of the Japanese and Korean phonetic systems: o Japanese: There are two phonetic symbol sets: katakana and hiragana. In gen- eral, you use katakana for words that are of foreign origin, and hiragana for writing native Japanese words. Collectively, the two systems are called kana. Each set consists of approximately 50 characters. You type either kana or English characters and define the region that you want to convert to 3 XIM Public Review Draft kanji. Several kanji characters may have the same phonetic representation. If that's the case with your string, you get a menu of characters and choose the appropriate one. If no choice is necessary, the input method does the substitution directly. When Latin characters are converted to kana or Kanji, it is called a romaji conversion. o Korean: Hangul is a writing system that actually straddles the line between phonetic and ideographic. It's phonetic in the sense that each of the roughly 25 characters represents a specific sound. But between two and five of the characters are combined to form syllables, and these syllables are the basic units on which text processing is done. For example, a delete operation works on a syllable rather than the individual characters within it. And Korean code sets include several thousands of these syllables. You type the hangul characters that make up the syllables of the words you're entering. The display changes as you enter each hangul letter. That is, when you enter the first letter, it fills the entire space that the final syll- able will take up. When you enter the second, the first shrinks to about half its size to make room for the second. When you enter the third, the first two shrink again. And so on, up to the maximum of five letters in a syllable. It's usually acceptable to keep Korean text in hangul form, but some words are more commonly written in hanja. If you want to change hangul to hanja, you define the region to be converted, and follow the same basic method as described for Japanese. Probably because there are well-accepted phonetic writing systems for Japanese and Korean, computer input methods for those languages are fairly standard. Keyboard keys have both English characters and the local language's phonetic symbols engraved on them. You can then switch the keyboard from English to local mode and vice versa. The situation is different for Chinese. While there is a phonetic system called Pinyin promoted by authorities, there is no consensus for entering Chinese text. Some vendors use a phonetic decomposition (Pinyin or another), others use ideographic decomposition of Chinese words, with various implementations and keyboard layouts. There are about 16 known methods, none of which is a clear standard. Also, there are actually two ideographic sets used: Traditional Chinese, (the original written Chinese) and Simplified Chinese. Several years back, the People's Republic Of China launched a campaign to simplify some ideographic characters and