What do Roman numerals represent in foreign patent publication dates?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

In foreign patent publication dates, Roman numerals have a specific purpose. According to MPEP 901.05(a):

“Roman numerals always refer to the month.”

This means that when you encounter a date in a foreign patent publication that uses Roman numerals, those numerals are consistently used to represent the month of the year. For example, VI would represent June, and XII would represent December.