This is the classification number given to books by China Library Classification, which is used to catalogue books. F stands for economic category. The first-level classification catalogue is as follows:

I Marxism-Leninism, Mao Zedong Thought and Deng Xiaoping Theory.

Philosophy, religion

Introduction to social science

Politics, law

E military

F economy

G. Culture, science, education and sports

H. Language and writing

I. Literature

J art

History, geography

Introduction to Natural Science China Library Classification

Mathematical science and chemistry

P astronomy, earth science

Q bioscience

Medicine and health

American agricultural science

technology

U transportation

V. Aviation and aerospace

X. Environmental Science and Safety Science

Z comprehensive books

There are also corresponding numbers under the first-level catalogue, which respectively represent the subdivided categories, that is, the small categories represented by a series of numbers in the year after the letter. The longer the number, the finer the classification, and the three digits of the number are marked with a dot. According to the regulations, the books on the bookshelf should be arranged in alphabetical order with the same number of digits from small to large. After you check the classification number of books on the computer, it will be much faster to find the books on the corresponding shelf in order (provided that the librarian doesn't put the books everywhere), hehe. F06 1.3 stands for development economics, and 5 1 should be the author's name code or other distinguishing numbers. I am a novice in the library, and I hope I can help you.