Document number. According to the national patent regulations, the patent number with a validity period of ten years is a document number. It is a serial number compiled by the Industrial Industry Bureau when granting patent rights. Each patent number is different and can be found in China Patent The patent number was found on the query system. The patent number for products belonging to inventions is valid for 20 years, while the patent number for new utility and design products is valid for 10 years.