ASC file format
Sure Larry,
AB:1 means that the "edge" from A-to-B is visible. BC:1 means that the
edge from B-to-C is visible. And CA:0 means that the edge from C-to-A is
invisible.
The normals are always derived from the order in which the faces is
triangulated. If it's triangulated in counter-clockwise order, the normal
faces towards you.
Hope that helps…
– G