There is no consistency in what parameters are exported to 3D model file types NWC, DWFx, FBX, IFC.
We use A360 to assist the site teams in construction but have noticed missing parameters in the DWFx files created.
Thread regarding the issue can be found here
http://forums.autodesk.com/t5/revit-mep-forum/missing-mep-offset-parameter-in-dwfx-from-revit-model-...