In 2002 the British Army's L118 guns completed replacement of their optical sights with the LINAPS artillery pointing system (APS) mounted above the barrel. This is a self-contained system that uses three ring laser gyros to determine azimuth, elevation angle and trunnion tilt angle. It also includes facilities for navigation and self-survey using a global positioning system, inertial direction measurement and distance measurement. All this can be used anywhere in the world to lay the gun without external references. The outputs and inputs for APS are through the touchscreen layer's display and control unit (LCDU) that replaced the conventional dial sight and its mount. The LCDU enables the layer to lay the gun by moving the barrel until the LCDU displays no difference between the ordered firing data and where the barrel is pointing as determined by the LINAPS sensors.