You're right – there are a few things that *are* in common between
low/mid-range 3D programs. The problem is, there is no one file format that
can be used to carry all that info, that is used by most 3D programs.
In another message, I recommended that DXF be extended to include other info
not present there now, in order to leverage the existing code base and support
for DXF into something better than DXF. It would also be possible to do this
with Wavefront ".obj" format, through the use of "conformal comments," that is,
comment lines that contain extra optional information such as hierarchy,
rotational centers, surface info, etc.