Analysis of the patent documentation coverage of the CPC in comparison with the IPC with a focus on Asian documentation

In this study we analyse the patent documentation coverage of the Cooperative Patent Classification system (CPC) in comparison with the coverage of the International Patent Classification system (IPC). We demonstrate that for patent searchers the coverage in terms of patent families is more relevant than the coverage in terms of patent documents. Of all the patent families classified in the IPC only about one third thereof is currently classified in the CPC. Most of the patent families that are not classified in the CPC are patent families including published patent applications filed at the three major Asian patent offices (JPO, KIPO and SIPO). We demonstrate a method of comparing the CPC patent documentation coverage to the IPC patent documentation coverage down to IPC subgroup level and how this can be applied to improve the efficiency of classification based search. The coverage of the CPC relative to the IPC must be understood in terms of: the CPC being assigned to families, and the IPC being assigned to individual documents. Furthermore, the CPC has only been implemented relatively recently compared to the IPC, with SIPO and KIPO focusing on the classification of their front files in the CPC.