Decomposition for ISO/IEC 10646 Ideographic Characters

Ideograph characters are often formed by some smaller functional units, which we call character components. These character components can be ideograph radicals, ideographs proper, or some pure components which must be used with others to form characters. Decomposition of ideographs can be used in many applications. It is particularly important in the study of Chinese character formation, phonetics and semantics. However, the way a character is decomposed depends on the definition of components as well as the decomposition rules. The 12 Ideographic Description Characters (IDCs) introduced in ISO 10646 are designed to describe characters using components. The Hong Kong SAR Government recently published two sets of glyph standards for ISO10646 characters. The standards, being the first of its kind, make use of character decomposition to specify a character glyph using its components. In this paper, we will first introduce the IDCs and how they can be used with components to describe two dimensional ideograph characters in a linear fashion. Next we will briefly discuss the basic references and character decomposition rules. We will then describe the data structure and algorithms to decompose Chinese characters into components and, vice versa. We have also implemented our database and algorithms as an internet application, called the Chinese Character Search System, available at website http://www.iso10646hk.net/. With this tool, people can easily search characters and components in ISO 10646.