If the address of the addressee cannot be established, or if service in accordance with Article 64(4) has proved to be impossible even after a second attempt by the Office, service shall be effected by public notice, to be issued in the periodical publication referred to in Article 89 of the basic Regulation. The President of the Office shall determine details as to the issue of a public notice and shall determine the period within which the relevant document shall be deemed to have been notified.