From one couple behind another or from couples back to back: Those in the lead (or those designated) roll back, turning away from the center, and join arms with the trailing dancer. Those casting back are on the ends of a line. From couples back to back, finishes in a regular line of four; from one couple behind another, finishes in a line with ends facing one way and centers facing the opposite way.
Vern Smith 1965
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.