For patents, we use the DOCDB simple family definition. This means, all patents that have the same combination of priority applications form one patent family. However, in a few cases, the priority document(s) itself is/are not part of the family, but in a different family or even a family of their own. This happens, for example, when the priority application itself was never published or the priority filings listed vary slightly. In these cases we add the priority artificially to the family. This is very important for precise case exchange calculations.
In short, our patent family definition is a little broader than the simple family definition, but smaller than the extended family or INPADOC family which includes all patents that share at least one mutual priority application.
In the trademark world, families do not exist. As such, we artificially create families when a combination of similarities, in verbal elements, images, representatives in different jurisdictions, etc, are identified in the raw data.