The EPO keeps a patent family system based on application data and priority data of the patent documents stored in databases of the EPO. When viewing patent documents on screen, normally only one representative document of a patent family is displayed, but links to the other members of its patent family are provided.
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/b_ix_2_4.htm
Date retrieved: 17 May 2021