Gets the first slot in the virtual function table (v-table or VTBL) that contains user-defined methods.
The first VTBL slot that contains user-defined methods. The first slot is 3 if the interface is based on tp://go.microsoft.com/fwlink/?LinkId=148003, and 7 if the interface is based on IDispatch.
This method returns the zero-based v-table number for an interface or a class. When used on a class, the slot number that is returned refers to the class interface for the class. If the class interface is auto-dispatch, this method always returns -1 to indicate that the dispatch-only interface does not expose a v-table to managed clients. You can use Marshal.GetStartComSlot(Type) and Marshal.GetEndComSlot(Type) in conjunction with Marshal.GetMethodInfoForComSlot(Type, int, ComMemberType@) to pass slots within a specified range. For additional information, see Introducing the Class Interface.