Reading XREF tree from external exe

Hi all,

I am trying to read the xref tree from a DWG by using an external exe. The app should simply open the DWG and sys-out the referenced paths and whether or not they are nested.
For this, I am using Autodesk.AutoCAD.Interop.
The problem is that I can only get a list of file dependencies (document.FileDependencies) and I can't seem to find an "isNested" value.
Is this even possible?

So far I've got:

AcadDocument document = oAcadApp.Documents.Open("Test.dwg");
foreach (AcadFileDependency o in document.FileDependencies)
{
 System.Console.Out.WriteLine(o.FullFileName);
}

There is also the option to get Blocks, but again there is no "isNested" info, only "isXref":
foreach (AcadBlock b in document.Database.Blocks)
                {
                    if (b.IsXRef)
                    {
                        ...doStuff...
                    }
                }

Any help would be very appreciated :)