Section 255(4) in The West Bengal Motor Vehicles Rules, 1989
(4)Each such chock shall be linked with the tail-board or, where the vehicle has no tail-board, with the wooden planks above the frame side members, by means of a metal chain or steel wire rope of sufficient length and strength, fastened to the hook in the chock and to the hook in the tail-board or the wooden planks, as the case may be.
