1. Definitions 

"Preclassification" is a first stage of classification using appropriate classification symbols to broadly identify the subject-matter of the claimed invention (or the invention first claimed if there is more than one) for the purposes of internal application (file) routing and allocation.

"IPC classification" involves assigning the appropriate classification symbols under the International Patent Classification (IPC) scheme published by WIPO. See the WIPO website for the IPC edition currently in force, and the "Guide to the IPC", which explains the principles and rules of IPC classification.

"CPC classification" involves assigning the appropriate classification symbols under the Cooperative Patent Classification (CPC) scheme published by the EPO and the USPTO. See the CPC website for the CPC edition currently in force, and the "Guide to the CPC", which complements the "Guide to the IPC" in that it deals with the differences between the CPC and the IPC.