The IPC classification of the patent application is performed by the search division.
The IPC classification identifies all features relevant to the technical subject of the claimed invention (or of the subjects of each of the claimed inventions if there is more than one) as precisely and comprehensively as the IPC scheme permits.
The IPC classification consists of "invention information" symbols and "additional information" symbols (the latter encompassing the usage of IPC indexing codes) according to the IPC rules defined in the "Guide to the IPC". In addition, where it is necessary to assign more than one symbol for the invention itself, the symbol which in the search division's opinion most adequately identifies it, or, when this presents difficulties, the symbol which identifies the invention for which most information is given, is indicated first. Preferably, this classification is done when the search division has studied the content of the application in order to carry out the search. However, if publication of the application is due before the search report is drawn up, it is necessary for the search division to study the application sufficiently to determine the IPC classification at this earlier stage (see B‑X, 5).
The IPC classification is determined without taking into consideration the probable content of the application after any amendment, since this classification relates to the disclosure in the published application, i.e. the application as filed. If, however, the search division's understanding of the invention, or of the content of the application as filed, alters significantly as a result of the search (e.g. as a result of prior art found or because of clarification of apparent obscurities), the search division will amend the classification accordingly, if the preparations for publication have not at that stage been completed.