Anilv
Yes it was the shuttle bar. Initially, the in-hold system in the DC-10 was a pleasant change after the 747. The hold had a nice flat floor without the deep "bilges" of the 747 which used to accumulate all manner of rubbish. Ostensibly the DC-10 in-hold system was designed for maximum flexibility. If I recall correctly, the ULDs were restrained by the fixed end stops at one end and the shuttle bar with flip-up locks behind it at the other. The ULDs were simply butted up against one another. Problems soon arose when pallets with warped edges began to override one another - "shingling" as they called it. With several empty pallets adjoining, fore and aft restraint was lost if pallets began to overlap. The solution was to fit all pallets with override blocks but it was a band-aid fix at best.