From parallel waves: Ends Trade then Roll. Centers Flip into the vacated end spots and then Roll and move into the center to Swing Thru and Turn Thru to rejoin the waves. Finishes in parallel waves (right hand end in right hand; left hand in left hand).
NOTE: "Flip" is coming to mean that certain dancers will run or fold or roll into an adjacent spot that has just been vacated by another dancer. It involves a reversal of facing direction. It doesn't always have this meaning, however.
Vince Di Caudo 1973
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.