Ordnance provision system. [Ordnance catalog (ordnance provision system): [Group F], Mount, telescope, M21, quadrant, range, M4, telescope, elbow, M16, mount telescope, M23 (for elbow telescope), major items, maintenance parts, and equipment required for maintenance of mount, telescope, M21, quadrant, range, M4, telescope, elbow, M16, mount telescope, M23 (for elbow telescope), addendum, Changes 1; Aug. 3, 1942.