14 C.F.R. § 48.1 – Applicability.

(a) This part provides registration and identification requirements for small unmanned aircraft that are part of a small unmanned aircraft system as defined in § 1.1 of this chapter.
(b) Small unmanned aircraft eligible for registration in the United States must be registered and identified in accordance with either:
1. (1) The registration and identification requirements in this part; or
2. (2) The registration requirements in part 47 and the identification and registration marking requirements in subparts A and C of part 45.
(c) Small unmanned aircraft intended to be operated outside of the territorial airspace of the United States, or registered through a trust or voting trust, must be registered in accordance with subparts A and B of part 47 and satisfy the identification and registration marking requirements of subparts A and C of part 45.