Jeff Kaufman wrote: The section "Diagramming Dances" in Cary Ravitz's "Notes on Choreography for Duple Minor Improper Contra Dances" https://www.dance.ravitz.us/chor.php describes a system similar to the one in Jeff's message. Note, however, that Cary places the top of the set at the right side of the page, so that when it is helpful to diagram more than one foursome, the contra line extends horizontally rather than vertically. --Jim