Autodesk DWG is a proprietary 3D geometry format native to Autodesk AutoCAD. Even though it doesn't have modern material support it is widely used in the BIM and CAD industries.
In addition to the general export options, DWG has the following option:
|Flip vertical axis of textures|
Flips the textures along the vertical axis. This is necessary as Autodesk AutoCAD and Autodesk TrueView employ different orientations.