>INNER_CONTROL to INNER_OTHER_CONTROL is not permitted, but INNER_CONTROL to OUTER_CONTROL is.
No, I'd say INNER_CONTROL to INNER_OTHER_CONTROL is permitted. Only inner_object of INNER_CONTROL to inner object of INNER_OTHER_CONTROL is forbidden.

Put even simpler: CONTROLS as inner objects of outer CONTROLS simply are encapsulation within encapsulation.

Bye, Olaf.