Use classification to search, and its search identifier is classification number. Classification number is a set of codes given to file entities in the form of types to fix and reflect the arrangement order of files.

The classification method searches documents according to the subject classification system. This method takes the knowledge system as the center, so it can better reflect the subject system, reflect the subordinate, derivative and parallel relationship between subjects and things, facilitate the search for literature materials from the subject range, and play an analogy role. Classified retrieval mainly uses classified catalogue and classified index.

Extended data

A large number of concepts expressing the contents of literature information and retrieval topics are classified and arranged according to their disciplinary nature, which has become a logical system that basically reflects the usual classification system of scientific knowledge, and a retrieval language that uses numbers (classification numbers) to express concepts and their positions in the system, and even to express the relationship between concepts. ?

China Library Classification is the basis of China Library Classification, and China Library Classification divides all knowledge categories into Marxism-Leninism and Mao Zedong Thought according to the five-point method. Philosophy; Social science; Natural science; Five categories of comprehensive books. On this basis, a system series consisting of 22 categories is constructed.

Baidu encyclopedia-classification number

Baidu Encyclopedia-Literature Retrieval