TWELVE REEL 
Square of threesomes.
64-bars of lively reel or jig; Russian Cavalry suggested.

A1: MEET AND TRADE  (as in TWELVE MEET); heads forward, back, forward, and
    end people change places and fall back with the other middle.
A2: sides the same
B1: heads the same
B2: sides the same (all home)
C1: 1-4: DANCE AROUND (middles and right-hand partners orbit the center of
         the set (chasse or polka step); right hand person ends up in 
         left hand place while left-hand person moves into right-hand place)
    5-8: Same with new right hand person.

C2: Sides the same.

D1: BASKET SWING (in threesomes)
    If you want to trade middles, this is the time to do it.

D2: CIRCLE: All 12 join hands and circle left once round, polka step.