Controller is the controlling IUnknown interface for the inner object in an aggregate. The QueryInterface, AddRef, and Release methods of all other interfaces of the inner object (except IUnknown) must delegate to the controlling IUnknown. Because of this delegation, the inner object's reference count is not affected when these methods are called. 

Controller is nil (Delphi) or NULL (C++) if the object is not part of an aggregate. If Controller is not nil (Delphi) or NULL (C++), the object is part of an aggregate, and Controller is the controlling interface. 

Create_c 

CreateAggregated 

TAggregatedObject 

TComObjectFactory 

TContainedObject