Ordnance provision system. Ordnance catalog (ordnance provision system): Group A. Gun, 37-mm, M3 and M3A1 and carriage, gun, 37-mm, M4 and M4A1, major items, maintenance parts and equipment required for maintenance of gun, 37-mm, M3 and M3A1 and carriage, gun, 37-mm, M4 and M4A1, addendum; Dec. 12, 1942.