I just received this from Robert Woodbury!

"Non-manifold representations present a general solution to problems presented by designs with internal structure, that is, all buildings. They can provide new, needed and elegant foundations on which to build more understandable and reliable CAD and BIM systems. Invented, starting in the 1980’s, non-manifold representations have not yet been widely adopted in practice. I am delighted that Topologic may change this, and help clarify, simplify and empower future CAD and BIM systems."