42 U.S. Code § 12141 - Definitions
The term “demand responsive system” means any system of providing designated public transportation which is not a fixed route system.
The term “designated public transportation” means transportation (other than public school transportation) by bus, rail, or any other conveyance (other than transportation by aircraft or intercity or commuter rail transportation (as defined in section 12161 of this title)) that provides the general public with general or special service (including charter service) on a regular and continuing basis.
The term “fixed route system” means a system of providing designated public transportation on which a vehicle is operated along a prescribed route according to a fixed schedule.
The term “operates”, as used with respect to a fixed route system or demand responsive system, includes operation of such system by a person under a contractual or other arrangement or relationship with a public entity.
The term “public school transportation” means transportation by schoolbus vehicles of schoolchildren, personnel, and equipment to and from a public elementary or secondary school and school-related activities.