From couples back to back: The belles do half a Zoom (Cast Back and walk straight ahead about two steps) as the beaux Flip into the vacated spot. The mirror image or "left-hand" version of this would be called Beaux Lead Back. Finishes in box formation.
Hugh Armstrong 1976
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.