4. CPC classification of the application 

Besides assigning an IPC classification, the search division also classifies a patent application under the CPC. In practice, the CPC classification is assigned first, and the relevant IPC symbols are then generated from the CPC ones by one-to-one concordance (see the CPC to IPC Concordance List, published on the CPC website).

The CPC classification should be as precise and comprehensive as possible under this classification scheme. The CPC comprises "invention information" symbols and "additional information" symbols. Additional information symbols include CPC indexing codes. If more than one CPC classification symbol has to be assigned for the invention itself, the symbol which, in the search division's opinion, best identifies it ‒ or, if that is not straightforward, the one identifying it for which most information is given ‒ is indicated first.

Like the IPC classification, the CPC classification should preferably be assigned after the search division has studied the content of the application to decide how to carry out the search.

Again like the IPC classification, the CPC classification relates to what is disclosed in the published application, i.e. the application as filed, and so is determined without taking into consideration what the application could potentially contain if it is later amended.

However, if the search division's understanding of the invention, or of the content of the application as filed, changes significantly during the search, it will change the CPC classification accordingly, using the appropriate classification tools. Unlike a change to the IPC classification (see B‑V, 3 above), this change can be made even after the preparations for publication have been completed.

If the scope of the invention is unclear (e.g. a partial search is necessary) or if there is a lack of unity of invention, the principles described in B‑V, 3.2 and 3.3 for the IPC classification apply equally to the CPC classification.