Section 186(1) in The Bihar Motor Vehicles Rules, 1992
(1)No person shall drive and no person shall cause or allow to be driven, in any public place any motor vehicle to which a trailer is or trailers are attached unless there is exhibited on the front of such motor vehicle and on the back of the trailer or of the last trailer in train, as the case may be, a distinguishing mark in the form set out in the diagram contained in the Fourth Schedule to these rules, in white on a black ground.
