From columns: Lead two dancers promenade in single file around the end of the adjacent column and down to the forward end to face in as a couple. Meanwhile, the trailing two do a double pass thru with each other, then turn a quarter to face out and step forward as a couple to join the other couple in a two faced line. Finishes in parallel two faced lines. NOTE: This is also called Checkmate The Column.
H.P. Williams 1975
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.