The Hand Signals ClipArt gallery provides 37 examples of hand and finger positions with specific meanings, particularly as used in trading commodities.
"To announce range, extend the arm toward the leaders or men for whom the signal is intended, fist closed;…
"To change elevation, indicate the amount of increase or decrease by fingers; point upward to indicate…
"Extend the arm horizontally toward the platoon leader; describe small circles with the hand." —…