The 1999 Report of the UN Panel of Governmental Experts on Small Arms provides a more refined and precise definition, which has become internationally accepted. This distinguishes between small arms (revolvers and self-loading pistols, rifles and carbines, submachine guns, assault rifles, and light machine guns), which are weapons designed for personal use, and light weapons (heavy machine guns, hand-held under-barrel and mounted grenade launchers, portable anti-aircraft guns, portable anti-tank guns, recoilless rifles, portable launchers of anti-aircraft missile systems, and mortars of calibres less than 100 mm), which are designed for use by several persons serving as a unit. Ammunition and explosives also form an integral part of small arms and light weapons used in conflict.