Article 149¹⁷³
Joint designation

(1) The group of Contracting States may provide that these States may only be designated jointly, and that the designation of one or some only of such States shall be deemed to constitute the designation of all the States of the group. 

(2) Where the European Patent Office acts as a designated Office under Article 153, paragraph 1, paragraph 1 shall apply if the applicant has indicated in the international application that he wishes to obtain a European patent for one or more of the designated States of the group. The same shall apply if the applicant designates in the international application one of the Contracting States in the group, whose national law provides that the designation of that State shall have the effect of the application being for a European patent.