Section 220(a) in The Bihar Motor Vehicles Rules, 1992
(a)No person shall drive, or suffer or cause to be driven, in any public place any motor vehicle to which trailer is or trailers are attached unless there is exhibited on the back of trailer or of trailers 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 fifth schedule to these rules in white on a background.
