Where is the documentation for Autodesk.AutoCAD.Interop?

I've looked in the ObjectARX SDK, in AutoCAD Help, on the Autodesk Developer Network, in SO and the broader internet, but I can't find documentation for the Autodesk.AutoCAD.Interop dll, only documentation for the in-process .NET API.

For example, there's plenty of info about the Application object:

http://docs.autodesk.com/ACD/2013/ENU/index.html?url=files/GUID-4E1AAFA9-740E-4097-800C-CAED09CDFF12.htm,topicNumber=d30e712496

...but no similar information about the AcadApplication object exposed by Autodesk.AutoCAD.Interop. Where can I find detailed information about the interop API?

There are some examples of using it to start AutoCAD:

http://through-the-interface.typepad.com/through_the_interface/2007/12/launching-autoc.html

How to close a file in Autocad using C# keeping acad.exe running?

...etc. But I'm looking for object graphs, method descriptions, etc. for the interop API, i.e., the kind of information available for the in-process .NET API.

I asked this on the Autodesk forums and learned that the documentation for the interop dll's can be found by looking up the documentation for the old VBA interface.