That appears essentially correct - the general syntax for referencing a control on a subform is:
Forms![main form name]![subform control name].Form![control name]
and having the subform control in a tab control doesn't really alter the method of referring to it, even if the actual subform is contained within a subform on a tab control.
Wendell
Colorful Colorado
You can't see the view if you don't climb the mountain!