Section 186 in The Bihar Motor Vehicles Rules, 1992
186. Distinguishing mark for trailers.
(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.(2)The mark shall be kept clean and unobscured and shall be so fixed to the trailer that-(i)the letter on mark is vertical and easily distinguishable from the rear of the trailer,(ii)the mark is either on the centre or to the right hand side or the back of the trailer, and(iii)no part thereof is at a height exceeding 120 centimeters from the ground.Chapter-VIII Control of Traffic
