(a) From two couples one directly behind the other and both
facing the same direction: The couple in front will make
an arch and backup as the couple behind ducks thru the arch
to exchange places.(b) From Trade Bv formation: The center couple make an arch and
back over the outside couple to end in Eight Chain Thru.
What about right-/or lefthanded columns? Legal or illegal?
Who will make the arch?
Substitute [C1] (added to C1 in 2004): From Generalized Columns. Centers raise joined hands to make an arch and (moving toward the nearest Outsides) move forward or backward as the Outsides move into the Center. The traffic pattern has the Centers moving around the Outsides. Substitute exchanges the Centers with the Outsides. Nobody changes their facing direction during this call, and, in practice, dancers rarely make the arch. From Tandem Couples, Lead Couple arch & back up as Trailing Couple Steps Ahead (Circulate).
Hence Substitute is legal from any Columns. Centers make the arch.