section_path: Classification/Structural analysis
section_name: Structural analysis
paragraph_text: Structural analysis
  
  Most characters can be analysed structurally as compounds made of smaller components (部件; bùjiàn), which are often independent characters in their own right, adjusted to occupy a given position in the compound. Components within a character may serve a specific function: phonetic components provide a hint for the character's pronunciation, and semantic components indicate some element of the character's meaning. Components that serve neither function may be classified as pure signs with no particular meaning, other than their presence distinguishing one character from another.
  
  A straightforward structural classification scheme may consist of three pure classes of semantographs, phonographs and signs —having only semantic, phonetic, and form components respectively, as well as classes corresponding to each combination of component types. Of the 3500 characters that are frequently used in Standard Chinese, pure semantographs are estimated to be the rarest, accounting for about 5% of the lexicon, followed by pure signs with 18%, and semantic–form and phonetic–form compounds together accounting for 19%. The remaining 58% are phono-semantic compounds.
  
  The Chinese palaeographer Qiu Xigui (b. 1935) presents three principles of character function adapted from earlier proposals by Tang Lan (1901–1979) and Chen Mengjia (1911–1966), with semantographs describing all characters whose forms are wholly related to their meaning, regardless of the method by which the meaning was originally depicted, phonographs that include a phonetic component, and loangraphs encompassing existing characters that have been borrowed to write other words. Qiu also acknowledges the existence of character classes that fall outside of these principles, such as pure signs.