Talking about a unified coding standard, many people may have heard of Unicode. They may wonder whether Unicode is compatible with the ISO 10646 standard.

Unicode is a character coding system designed by the Unicode Consortium to support the interchange, processing and display of the written texts of all major languages in the world. Members of the Unicode Consortium are mainly hardware and software vendors.

In 1991, the ISO and the Unicode Consortium decided to cooperate in defining a universal coding standard for multilingual texts. Since then, the two organizations have been working very closely to extend the ISO 10646 standard and Unicode, and to keep them synchronized. The ISO releases information of characters and code points in the ISO 10646 standard, while the Unicode Consortium supplements the characters and code points with implementation algorithms and semantics information. The ISO 10646 standard and Unicode are code-to-code identical. Unicode can be regarded as the implementation version of the ISO 10646 standard. Therefore, products supporting Unicode also support the ISO 10646 standard.

Unicode 3.0 was officially released by the Unicode Consortium in February 2000. It contains 49,194 characters of different languages, in which 27,484 are East Asian (Han) ideographic characters. Unicode 3.0 is synchronized with ISO/IEC 10646-1:2000.

Unicode 3.1 was released in March 2001. The main feature of Unicode 3.1 is the addition of 44,946 new characters, in which 42,711 are ideographic characters. Together with the existing characters in Unicode 3.0, Unicode 3.1 has 94,140 characters, in which more than 70,000 are ideographic characters.

Unicode 4.0 was released in April 2003. It covers 1,226 new characters but the ideographic characters included are still the same as Unicode 3.1. Unicode 4.0 is synchronized with the ISO/IEC 10646:2003.

Unicode 4.1 was released by the Unicode Consortium in March 2005, which corresponds with the ISO/IEC 10646:2003 and its Amendments. The latest version of the Unicode Standard is version 5.0 released in July 2006, in which the ideographic characters included are the same as Unicode 4.1.

Information on the characters included in the ISO 10646 standard / the Unicode standard is available on the web site of the Unicode Consortium at http://www.unicode.org/charts/.