DWG (DraWinG) is the standard file format of AutoCAD drawings.
DXF (Drawing eXchange Format) is a universal file format.
All CAD and CAM programs can open it, so they use this to import in other CAD en CAM products if they aren' t sure if it can read a DWG file.
If this is possible to implement maybe you can add DWF (Drawing Web Format) support.