2 C.F.R. § 1201.2
Throughout this part, the term "DOT Component" refers to any Division, Office, or Mode (e.g., the Federal Aviation Administration (FAA), Federal Highway Administration (FHWA), Federal Motor Carrier Safety Administration (FMCSA), Federal Railroad Administration (FRA), Federal Transit Administration (FTA), Maritime Administration (MARAD), National Highway Traffic Safety Administration (NHTSA), Office of Inspector General (OIG), Office of the Secretary of Transportation (OST), Pipeline and Hazardous Materials Safety Administration (PHMSA), St. Lawrence Seaway Development Corporation (SLSDC), and the Surface Transportation Board (STB)) within the Department of Transportation awarding Federal financial assistance. In addition, the term "DOT Headquarters" refers to the Secretary of Transportation or any office designated by the Secretary to fulfill headquarters' functions within any office under the Secretary's immediate supervision.
2 C.F.R. §1201.2