Knowing the material layers of objects (e.g. wall is 1 layer plasterboard, 1 layer stud, 1 layer plasterboard) is one of the most important, fundamental aspects of BIM model exchange.
The IFC4 Reference View MVD is the only IFC4 MVD that has a “final” status. Therefore, this is pretty much the only type of IFC4 data that we can get from people still trying to play nice with the whole MVD concept.
The IFC4 Reference View MVD does not include material layers.
I think this is a problem. Enough that we cannot specify this MVD any more in contracts because it basically means any vendor producing this MVD is not producing useful information for us.