I've got a number of hierarchy demo images floating around from over the years. Would any of these be the kind of thing you mean?
Most simplistic hierarchy possible:

A typical working hierarchy (Light/geometry names unimportant - they're just to label them to give a clearer idea of what is glued to what):

How PCS2 will read objects and object groups:

Faulty hierarchy due to having object groups that contain only other object groups - no geometry of their own:

Various hierarchies and how they will be interpreted by PCS2. Especially the ones on the right, since those could be interpreted and saved like that by 3D exploration, possibly allowing programs like Sketchup to save PCS2 compatible COBs without needing Truespace at all:
