Geometry:
- No isolated vertices
- No coincident vertices
- No coincident/coplanar faces
- Correct face normals
- No empty objects
- No open edges or borders

Topology:
- Quads and Triangles only
- Model can be cleanly subdividable

Other:
- lighting and cameras are not included in the product
(Model file includes only the 3D model)
- Model Scale: real-world scale
- Model after 'reset xForm'
- Model centered at origin (0,0,0)
- all objects are named and logically grouped