Derek: coord_factor was and still is as i have documented.  It is difficult to explain these things succinctly in documentation.  I think the previous documentor thought of the transformation as "what i do to the mesh to put it into my simulation's reference frame" whereas i have documented it as "what i do to my simulation's points to place them into the mesh"  Either is valid of course: the latter was a tiny bit easier for me to document, and is how the code actually works.
Ben - thanks