E = D + standard marshaller (allowing non-C/C++ clients including .NET client)

**** .idl ****

interface IXxxx : IUnknown

library XxxxLibrary
    coclass CoXxxx

**** .h ****

class CoXxxx : ITest
// IUnknown methods
// IXxxx methods

class CoXxxxFactory : IClassFactory
// IUnknown methods
// IClassFactory methods

**** registry ****

name -> co class GUID
co class GUID -> name
co class GUID -> DLL
co class GUID -> library GUID
library GUID -> library

**** C++ usage ****

import tlb

IXxxxPtr p
IXxxxPtr.CreateInstance()

or:

IXxxxPtr p()

**** C# usage ****

CoXxxx co = new CoXxxxClass()
IXxxx o = (IXxxx)co