UNOS (in the Northern hemisphere) - Undershoot North, Overshoot South. To compensate for magnetic dip when turning. ONUS in the Southern hemisphere.[1]
^Lindsey, Ivan (2012). In the heavens above : British Commonwealth Air Training Plan : RNZAF aircrew training Canada 1940-1945. Christchurch, N.Z.: Willsonscott Pub. p. 310. ISBN9781877427381.