14 CFR § 71.11
Air Traffic Service (ATS) routes
July 13, 2020
Unless otherwise specified, the following apply:
(a) An Air Traffic Service (ATS) route is based on a centerline that extends from one navigation aid, fix, or intersection, to another navigation aid, fix, or intersection (or through several navigation aids, fixes, or intersections) specified for that route.
(b) An ATS route does not include the airspace of a prohibited area.
[Doc. No. FAA-2003-14698, 68 FR 16947, Apr. 8, 2003, as amended by Amdt. 71-33, 70 FR 23004, May 3, 2005]