System.Runtime.InteropServices.Marshal include AddRef and its counterpart Release
GetComInterfaceForObject (returns IntPtr)
GetIUnknownForObject (returns IntPtr)
GetIDispatchForObject (returns IntPtr)
QueryInterface
AllocCoTaskMem
GetEndComSlot
IsComObject
GetObjectForIUnknown (returns System.Object) AddRef and Release methods require such a pointer in their argument.