However, in many cases, a European application will claim the right of priority of the date of filing of a previous application. In such cases, it is the priority date (i.e. the date of filing of the previous application) which becomes the effective date for the purposes mentioned in the preceding paragraph.[Art. 89; ]
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/f_vi_1_2.htm
Date retrieved: 17 May 2021