The Boy Scout Wilderness Survival Merit Badge requires that the scouts describe (I have them construct) 5 ground to air signals: V, X, N, Y, and the arrow. According to the merit badge pamphlet, the V means require assistance, the X means require medical assistance, N for no, Y for yes, and the arrow for the direction of movement.

Even if the aerial rescue misinterprets the meaning of a signal, if they saw it they have located the isolated individual or group.