The Null Object is a special object reference that is guaranteed to never point at a valid object heap variable. It is used by IDL to initialize object reference variables when no other initializing value is present. It is also a convenient value to use when defining structure definitions for fields that are object references, since it avoids the need to have a pre-existing valid object reference.
Null objects are created when you call an object-creation routine but do not specify a class structure to be used as the new object's template. The following statement creates a null object:
nullobj = OBJ_NEW()