The _AddRef method implements the IUnknown AddRef method. Do not call the protected _AddRef method directly. _AddRef is called through the IUnknown interface to indicate that another object is using the owner's interface pointer. When the other object is through with the interface, it calls _ Release through the IUnknown interface. This allows the class to free its owner when it is no longer used (when the reference count goes to zero).
_AddRef increments the RefCount.TRefCount.RefCount property.