The "tituli picti" on the Monte Testaccio amphorae tend to follow a standard pattern and indicate a rigorous system of inspection to control trade and deter fraud. An amphora was first weighed while empty, and its weight was marked on the outside of the vessel. The name of the export merchant was then noted, followed by a line giving the weight of the oil contained in the amphora (subtracting the previously determined weight of the vessel itself). Those responsible for carrying out and monitoring the weighing then signed their names on the amphora and the location of the farm from which the oil originated was also noted. The maker of the amphora was often identified by a stamp on the vessel's handle.