"China Library Classification Number" refers to the classification code obtained by analyzing the theme of scientific and technological documents by using "China Library Classification" and organizing the documents in different categories according to the theme attributes and characteristics of the documents.

Classification and theme reveal and organize documents from the perspective of document knowledge content. Classification is to reveal and organize documents according to their subject knowledge attributes, and classification number is based on certain classification tools, with letters or/and numbers as the identification symbols of categories.