Good question – and very pertinent to the present discussion of the larger picture.

Generally, the fractals subdivide with the following labels:

A would subdivide in a triangle, flat, and expanded flat as “abc”
A would subdivide 1,2,3,4,5 in a Zig-Zag

B would always subdivide abc
C would always subdivide 1,2,3,4,5 except in the case of a triangle when it also becomes abc fractal.

I hope this wasn't too confusing an explanation.