From lines facing in or parallel waves: Ends face out as the centers "Crosstrail" with each other (no Pass Thru) and walk forward to form lines facing out. (From regular lines, the centers remain centers.) From waves, the centers do a Single Hinge type action and walk ahead (in place of the Crosstrail). Centers originally facing in go to the centers of new lines. Centers originally facing out go to the ends of new lines.
Vern Smith 1964
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.