From parallel ocean waves:
   (1) The end dancer and adjacent center dancer in each
         wave trade (turn 1/2). For the new end dancers the
         call is finished.
   (2) The new centers of each wave cast off 3/4 to form a
         new wave at right angles to the original ones.
   (3) The center dancers of the new wave trade (turn 1/2).
         The end dancers in that wave MUST NOT MOVE.
   (4) After the trade, connect with the (stationary) ends
         and cast off 3/4 to complete the move.

After step (1) the caller may direct the ends to do something
while the centers complete the call.