The internal structures studies the relationship between the forms, sounds and meanings of Chinese characters.
Hierarchical dividing can display the external structure of Chinese characters, while plane splitting can be regarded as omitting the higher splitting levels, and directly writing out the final separating result of primitive components.
[8] An undecomposable character (独体字; 獨體字) consists of one primitive component, which is directly formed by strokes and can not be decomposed into smaller components, for example, "一, 二, 三, 止, 正".
[14] In Shuowen Jiezi, Xu Shen proposed six categories (六书; 六書; liùshū) of Chinese characters, including [15] The traditional liushu presupposed that every internal component, usually called pianpang (偏旁), can either represent the sound or meaning of the character.
But, after the long evolution of the Chinese writing systems, quite a few components can no longer effectively play the roles and have become pure form components, or pure signs.
Due to subsequent changes in the shape or pronunciation of the phonetic components or the characters, the phonetic components could not effectively represent the pronunciation of the character and became pure form.
[26] They mostly came from ancient semantic-phonetic characters, where the semantic components lost their functions and became pure form.
For example, Semantic-phonetic-form characters (义音记字; 義音記字; yìyīnjìzì) consist of the three kinds of components.
For example, 江 (river) is divided into components 氵and 工 in both cases.