Claiming priority
Article 20
If the applicant claims a right of priority for an application within the meaning of Article 52(2) of the basic Regulation, which is not the earliest of those to be indicated pursuant to the first indent of Article 18(3) of this Regulation, the Office shall state that a priority date can only be given to such earlier application. Where the Office has issued a receipt including the date of filing of an application which is not the earliest of those to be indicated, the priority date notified shall be considered void.