 Further, it was also referred to as "SPOS" (Strong-point-obstacle-system), with two different components, "Dump Truck" (anti-vehicle) and "Mud River" (anti-personnel), which were collectively referred to as "Muscle Shoals".USMC Engineers in early 1967 were ordered to bulldoze a strip to at least 500 meters wide from Gio Linh westward to Con Thien.This became known by the Marines as "The Trace".