such as when only one round or salvo was going to be fired (e.g. by nuclear artillery or a multiple rocket launcher), a director or aiming circle about 100 meters away could be used as an aiming point. Related matters Originally, when indirect fire was introduced, an aiming point (AP) was used as a quick means of orienting the guns by ordering an angle to the AP for all guns to use. Other aiming points were used for aiming while firing, initially called ‘supplementary aiming points’ were given the name ‘Gun Aiming Points’ (GAP). Many armies required that each gun recorded several GAPs, some mounted recording plates on their guns where the GAP angles were written, and some had regulations giving the priority order for the use of different types of GAP. In the 1980s the US Multi-Launch Rocket System entered US service, this did not use GAPs because it had a gyroscopic orientation system and did not need external reference points or orientation. During the 1990s similar systems were adopted by M109 Paladin, AS90 and Panzerhaubitze 2000, and subsequently they were adopted for towed guns, notably UK’s 105mm L118 Light Guns. See also Milliradian Ballistics