Biomedical Engineering Reference
Fig. 3.7 US patent office site and page for searches
• to use the Catchwords Index (Fig. 3.8 ) available in the WIPO website ( http://
therein is limited); or else
• to perform a search with the IPCCAT tool ( https://www3.wipo.int/ipccat/ ): bet-
ter results compared to the Catchwords Index are achieved (Fig. 3.9 ).
One of the main difficulties in using classification arises from the circumstance
that no unified scheme exists and accordingly the examiners or patent searchers
who query several databases must learn to recognize the various classification
systems (IPC, CPC, USPC, DEKLA, FI, F-terms, etc.). Some classification codes
apply to national patents only (USPC, FI, F-terms) and hence it is preferable to use
the IPC and CPC systems.
The primary aim of a classification system is the creation of an effective search
tool, but if a subgroup contains a high number of documents, it is unuseful at all!
This is the reason why classification codes are subjected to a revision by examin-
ers in the event of new technologies are available or when the size of subgroups is
too wide: the purpose is to make patent searches more efficient.