The difference between classification number and main classification number

The international patent classification number mainly identifies the patent documents of inventions and utility models. (International Patent Classification Table)

When the same patent application has multiple classification numbers, the first one is called the main classification number.

For example, when the appearance product has a product combination with two or more uses, the examiner will

Give some classification numbers corresponding to their uses. The classification number determined by the first use is the first-class classification number, and the classification number determined by the second use is the second-class classification number.