PATH Mac OS 8 and 9 Developer Documentation > Text Encoding Conversion Manager
Programming With the Text Encoding Conversion Manager

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About Unicode

Most character sets and character encoding schemes developed in the past are limited in their coverage, usually supporting just one language or a small set of languages. In addition, character encoding schemes are often complex, usually involving byte values whose interpretation depends on preceding byte values. Multilingual software has traditionally had to implement methods for supporting and identifying multiple character encodings.

A simpler solution is to combine the characters for all commonly used languages and symbols into a single universal coded character set. Unicode is such a universal coded character set, and offers the simplest solution to the problem of text representation in multilingual systems. Because Unicode also contains a wide assortment of technical, typographic, and other symbols, it offers advantages even to developers of applications that only handle a single language. Unicode provides more representational power than any other single character set or encoding scheme. However, because Unicode is a single coded character set, it doesn't require the use of escape sequences or other complexities to identify transitions between coded character sets.

Because Unicode includes the character repertoires of most common character encodings, it facilitates data interchange with other platforms. Using Unicode, text manipulated by your application and shared across applications and platforms can be encoded in a single coded character set; this text can also be easily localized.

Unicode provides some special features, such as combining or nonspacing marks and conjoining jamos. These features are a function of the variety of languages that Unicode handles. If you have coded applications that handle text for the languages these features support, they should be familiar to you. If you have used a single coded character set such as ASCII almost exclusively, these features will be new to you.

The following two bodies, involved in the effort to standardize the world's languages for use in computing, define Unicode standards:

• The Unicode Consortium, a technical committee composed of representatives from many different companies, publishes the Unicode standard. Version 2.0 of the Unicode Standard was published in July 1996. However, the standard is evolving constantly, and updates are posted at the Unicode Consortium Web site http://www.unicode.org/.

• ISO (the International Organization for Standardization) and the IEC (the International Electrotechnical Commission), two of the international bodies active in character encoding standards, publish ISO/IEC 10646. This standard specifies the Universal Multiple-Octet Coded Character Set (UCS), a standard whose code point assignments are identical with Unicode.

ISO/IEC 10646