The examiner classifies a patent application under the provisions of the CPC as well as the IPC. In practice, classification is first performed in the CPC, and the relevant IPC symbols are then generated from the CPC allocations by one-to-one concordance (see the CPC to IPC Concordance List (CICL), published on the CPC website).
The CPC classification allocated is as precise and comprehensive as the classification system permits. The CPC comprises "invention information" symbols and "additional information" symbols. Additional information symbols encompass the use of CPC indexing codes. Where it is necessary to assign more than one CPC classification symbol for the invention itself, the symbol which, in the examiner's opinion, most adequately identifies the invention, or, when this presents difficulties, the symbol which identifies the invention for which most information is given, should be indicated first.
As with the IPC, CPC classification should preferably take place when the examiner has studied the content of the application in order to carry out the search.
As for the IPC classification, the CPC classification should be determined without taking into consideration the possible future content of the application after any amendment, since the classification should relate to the disclosure of the published application, i.e. the application as filed.
However, if the examiner's understanding of the invention, or of the content of the application as filed, alters significantly as a result of the search, the examiner should amend the CPC classification accordingly, making use of the appropriate classification tools. Unlike changes to the IPC classification (see B-V, 3, above), this amendment can be made even after the preparations for publication have been completed.
When the scope of the invention is not clear (e.g. a partial search is necessary), or in case of 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.