WIPO Standard Application Number Formatting

Application numbers are given to each application received by an intellectual property office to allow unique identification.  Also, when priority is claimed from a document by subsequent applicants, the application number can be used.  A common presentation of application numbers is therefore essential, and WIPO has attempted to standardise the format.

WIPO suggests that an application number normally has a fixed length of 15 characters, with a 2-digit country code, 4-digit year designation, maximum of 7 digits for the serial number, and a 2-digit kind code.  Although the country code is not officially part of the application number, it should always precede the application number in written text.

Recommended Application Number Format

Country Code

The country code is given by two characters (alphabetic only) at the start of the application number and depict the designated country or territory of the filing of the application.  See What does a Patent Document Contain? for a more detailed description.  Entering an application without a country code into a patent search engine will still give you a result, but will be less accurate as all the applications with the same number will be found.

Year Designation

The year, according to the Gregorian calendar, indicates the year of filing of the application consists of 4 digits (if chosen to be included by the relevant IPO).

Serial Number

A fixed length of 7 digits for the serial number is preferential, however leading zeros can be omitted (but must be included to produce a machine-readable form).  Therefore, if a serial number has fewer than 7 digits, the missing positions after the year of filing may be filled by zeros.

Kind Code

A 2-character letter and number combination at the end of the serial number to denote the type of document.  See What does a Patent Document Contain? for a more detailed description.  Kind codes are not always added to application numbers so it is worth searching both with and without.

Check Digit

A check digit (otherwise known as a control number) is often used by several IP Offices as a code to reduce the probability of mis-typing a number and having it be accepted.  It is usually a single numerical digit preceded by a full stop at the end of the serial number.  The number can be ignored and left out of searches.


In practice separators such as a slash “/”, a hyphen “-“, or a space ” ” are regularly used to separate the different elements of an application number.  These should only be used for presentation and not inputted into an IP search database field as they are not part of the computer-readable form.


The easiest way to get you familiar with recognising application numbers is to give a few examples .  One  approach would be to list some examples which are formatted in the accepted way as described by the recommendations above.  However, although based on a combination of  the above rules, various IP Offices have many different ways of displaying the application number.  For a thorough list of examples of accepted forms of application numbers as per each IP Office, see Variations of Application Number Formatting by Country.