< < strong > > The first line of the label is the category number, which is the subject member code representing the contents of the book.

The second line is the distinguishing number, which is used to distinguish different books under the same subject code in our library. Some libraries use author codes, while others use secondary serial numbers.

At present, the domestic library classification mainly includes: China Library Classification (namely "China Library Classification"), National People's Congress Classification and Science Library Classification. It depends on what classification you want to know about this library.