Priority number is the number of the originally filed application that the subsequent applications is based upon. A priority number consists of a country code followed by the number of the originally filed application.
The majority of countries priority numbers are made up of a country code (two letters), the year of filing (four digits), and a serial number (variable, maximum seven digits).
Some countries use other formats. These are Australia, Germany, China, Brazil, Ukraine, Gulf Council, Hungary, India, Italy, Mexico, OAPI and WIPO. Their application numbers are made up of: