Definition of systematic classification: Systematic classification is a kind of literature classification based on scientific classification and based on the principle of concept division and generalization, which forms a hierarchical structure system with hierarchical membership and detailed enumeration. Also called enumeration classification, enumeration classification. Chinese Library Classification, DDC and LCC are all systematic classifications. The main table structure of system classification is a category table composed of basic categories, basic categories, summary tables and detailed tables, which is the main body of classification. For example: DDC: rational knowledge → imaginary knowledge → memory knowledge China library classification: Marxism-Leninism, Mao Zedong Thought, Deng Lun → philosophy, religion → social science → natural science → comprehensive library method: summary science → social science → natural science → comprehensive book classification: it is a document classification compiled according to the comprehensive principle of conceptual analysis, also known as faceted classification, combinatorial classification and analysis-synthesis method. It decomposes theme concepts into simple concepts (or conceptual factors) and arranges them into tables according to their aspects or categories. When indexing, a complex subject concept is represented by the combination of classification numbers of two or more simple concepts. Structure: Faceted combination classification can be divided into full faceted classification and half faceted classification. The total facet classification is a pure combinatorial classification, which is generally only used in small disciplines or majors. The professional faceted classification compiled by the London Classification Research Group belongs to this type. Its main body is a faceted table, in addition to the preparation and use of instructions, outlines, indexes, etc. The face class table consists of several groups of faces. Grouping surface is a group of categories produced by dividing a subject field with a single series of classification standards, that is, a group of simple concepts representing a certain attribute of a certain kind of things. For example, the classification of library branches divides the available library types, materials, business, disciplines, regions, times and other characteristics, thus generating six categories, namely six groups. Each group of faces can also be divided into two or more sub-faces by the same series of finer standards. These two classifications are quite different in structure and theme.