How often are USPC definitions updated?

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.

USPC definitions are regularly updated to reflect changes in patent classification. The MPEP states: It should be noted that classification orders frequently affect existing definitions. Personal sets of definitions used by examiners should be periodically revised to reflect these changes.

To keep examiners informed about these updates, the MPEP provides information on accessing Classification Orders: Classification Orders are available online to USPTO personnel from the Classification Home Page under the heading Classification Reports. The Classification Home Page is accessible from the desktop via the Patent Examiner’s Toolkit.

Additionally, the class definitions are archived twice a year: The class definitions are archived in portable document formats (PDFs) to CD-ROM every June and December. This regular archiving process ensures that historical versions of the definitions are preserved.