markings on trailer walls

Let me see if I can figure out what you are saying. Are you saying that in the "nose" of the trailer, for instance, the first 4-6 ft, there is this marking you described? It might be a marking for a certain shipper that your company uses and not all trailers have loaded there. The product loaded there might be a weight conscious item that has to be loaded a tad light in the nose. Years ago, I loaded at a shipper that used to lay down 2 empty pallets on the floor and then proceeded to load full pallets behind the emptys, so, the first 4' wasn't utilized and the full pallets wouldn't slide forward in transit.