Proposal to establish uniform provisions concerning the approval of M₂ and M₃ vehicles to assist in the prevention of children being left inside. This regulation applies to vehicles of categories M₂ and M₃ class B and III designed or equipped primarily for the carriage of children, or special purpose vehicles of categories M₂ and M₃ class B and III designed specifically for the carriage of children. Vehicles shall be equipped with a physical inspection system which satisfies the requirements, including that the system shall be engaged when the vehicle master control switch is turned off and shall generate an external visual and audible warning if not disarmed within three minutes for buses not exceeding 22 passenger seats, or within five minutes for buses exceeding 22 passenger seats. The audible warning shall be greater than 60 dB(A).