Introduction to Library Classification in China Library Classification in China (referred to as Chinese Library Classification) is a comprehensive classification widely used by libraries and intelligence units in China. By 1999, China Library Classification has been revised four times (focusing on F economy, TN radio electronics, telecommunications technology, TP automation technology and computer technology). ? China Library Classification is divided into 5 basic categories and 22 major categories. Chinese phonetic alphabet and Arabic numerals are mixed, one letter represents a big category, and the alphabetical order reflects the order of big categories, and the number after the letter is used as a mark. In order to adapt to the development of industrial technology and the classification of this kind of literature, the two-letter classification of industrial technology is adopted. The department names of China Library Classification are as follows: Marxism, Leninism, Mao Zedong Thought A Marxism, Leninism, Mao Zedong Thought Philosophy B Philosophy Social Sciences C Introduction to Social Sciences? D politics and law? Introduction to natural science? O mathematical science and chemistry? P astronomy, earth science? Q biological science? R medicine, health? Agricultural science? T industrial technology? U traffic? 5. Aerospace? X comprehensive books on environmental science and labor protection science Z comprehensive books