How can an applicant claim the priority of an earlier application?
A declaration in an international application claiming the priority of one or more earlier applications filed in or for any state party to the Paris Convention for the Protection of Industrial Property ("Paris Convention") or in or for any Member of the World Trade Organization (WTO) that is not party to the Paris Convention must always indicate the date on which the earlier application was filed, the state or states in which it was filed and the application number(s) under which it was filed. If the earlier application was a regional one, it suffices to give the name of the patent-granting authority under the regional agreement - i.e. "EP" in the case of a European application (Box No. VI PCT request form).
If the priority application was not filed by the applicant but transferred to him, the transfer must have taken place before the filing of the application. Proof of entitlement on the international filing date must be submitted (only) if the validity of the priority right claimed becomes relevant in the proceedings before the EPO.
Source: http://www.epo.org/applying/international/guide-for-applicants/html/e/ga_c2_13.html
Date retrieved: 17 May 2021