1. country code: indicates the country or region to which the patent belongs. Common country codes include the United States, China and European patent organizations.
2. classification code: indicates the classification of the technical field to which the patent belongs. Different countries or regions may adopt different technical classification systems. For example, the United States adopted the United States Patent Classification System (USPC) and China adopted the China Patent Classification System (CPC).
3. Serial number: The serial number of the patent is expressed by numbers, generally increasing from 1.
The specific format can be different according to the regulations of different countries or regions. For example, the format of American patent number is usually country code (two letters)+classification code (three digits)+serial number (four to six digits), such as US 1234567.
It should be noted that the national defense patent number is not available in all countries or regions, but is set by some countries or regions with national defense science and technology research and development institutions.