From a one quarter tag formation: In the wave arm turn half and the new ends give a left hand to the "beau" in the outside couple who courtesy turns them to face in. Meanwhile, the new centers (in the wave) arm turn half and the "belles" in the outside couple step up to become the ends of a two faced line in the center. Finishes with a two faced line between and parallel to two couples facing in.
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.