What does the patent application main classification number mean?

The classification systems of invention patents, utility model patents and design patents are different. The invention patent and utility model patent use IPC international classification number, and the design patent uses Locarno classification table. IPC international classification number, which divides the technical field into eight departments, and then divides them into divisions, categories, subcategories, large groups and groups in turn; Part A-Necessary for human life (agriculture, light industry and medicine); Part b-operation and transportation; Part c-chemistry and metallurgy; Part d-textiles and paper making; Part e-fixed buildings (construction, mining); Part f-mechanical engineering; Part g-physics; Part h-electricity. The main function of using classification number is to classify patent documents and patent retrieval. At the same time, through the patent number, we can know which technical field the patent belongs to and what its technical theme is, and we can also know the similar patents.