Kent Smith writes:  My use of the figure [9-20] was inspired by "The Three Rivers Reel" by Martin Mulligan.

Both on bars 12 and 16 1W and 3M pass Lsh and face R into the next half reel.  There is a variant where they pass a tight Lsh 3/4 round each other and face L; they thus change roles in the half reel across for [12-16].  From then on the variants are identical again. Eric Ferguson, march 2015. 