From parallel right hand waves: Center four do a Split (Box) Counter Rotate. Outside lead dancer rolls back to the left to Single Hinge with trailing outside dancer. Finishes in left hand column formation. From parallel left hand waves, the outside lead dancer rolls back to the right and it finishes in right hand column formation.
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.