2. International Patent Classification

Patent databases are constantly evolving, both in terms of the number of filings and the diversity of subjects covered. It is therefore impossible to carry out a keyword search, as in the case of scientific publications, for example. Patents do not contain keywords.

To ensure search stability, however, the patent examiner assigns a certain number of classes or sub-classes from the International Patent Classification. The number of classes is fixed, thus ensuring search stability. US and Japanese patents have their own classes, but in all cases, these are transcoded by international servers (such as WIPO or EP) into the international classification via correspondence tables.

Recently, the IPC (International Patent Classification) was extended via the CPC (Cooperative Patent Classification): The Cooperative Patent Classification (CPC) is an...