hmm....

I think I can solve the position by:

creating a tiny "node" object like a small cube as a subobject for each part
then can I get the position of the bounding box of the node.

but for orientation, I'd need to know the rotation of the node.

I thought maybe a cube (as a primitive) would have orientation.
But playing with "Separate" on a cube, I see that it's composed as 6 planes to enclose a solid.

So when we rotate, moi just transforms the vertices?

Jeff.