Consider a monthly event on last Friday. Now, we add an exception for 2016-09-30 and "move" it to 2016-10-14 (note it must be another week). It will create a vevent block with recurrence-id=2016-09-30 and dtstart=2016-10-14 and dtend=2016-10-14.

Such an event will not be displayed on 2016-09-30 nor on 2016-10-14 (where it should).