From columns of three side by side and facing opposite (two dancers are inactive): Lead two of each file single file promenade around the end of the adjacent column to the next position in the square to face in. Third dancer in each file moves ahead to arm turn the other 3/4 and then pull by to end facing out between two facing in in lines of three.
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.
