What is the purpose of the “Combination-Type” references in CPC classification?

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.

The “Combination-Type” references in CPC classification serve a specific purpose in patent examination. According to MPEP 905.03(b):

“Combination-Type” references list subgroups that, when combined with the subgroup in question, should be considered to determine if a further classification is necessary.

These references help examiners identify potential additional classifications for inventions that combine multiple elements or features. By considering these combinations, examiners can ensure a more comprehensive classification of patent applications, potentially improving search accuracy and efficiency.