(a) No person may operate a small unmanned aircraft registered in accordance with this part unless the aircraft displays a unique identifier in accordance with the requirements of § 48.205 of this subpart.(b) A unique identifier is one of the following:(1) The registration number issued to an individual or the registration number issued to the aircraft by the Registry upon completion of the registration process provided by this part; or(2) If authorized by the Administrator, the small unmanned aircraft serial number provided with the application for Certificate of Aircraft Registration under § 48.110(a) .Doc. No. FAA-2015-7396; Amdt. No. 48-1; 80 FR 78645 , Dec. 16, 2015. Redesignated and amended by Doc. No. FAA-2019-1100; Amdt. No. 48-3, 86 FR 4504 , Jan. 15, 2021