3.1. Recurrence properties modifications
3.1.1.
To reschedule an event to a set of explicit dates/times but not replace the set with a new rule pattern, the sender should send a set of components with RECURRENCE-ID being set in each to handle the explicit override of the rule’s date/time.
3.1.2.
If an RRULE is changed, then the entire iCalendar object should be resent in the reschedule. This tells the receiver that all exceptions should be removed and replaced with this new rule. The new RRULE properties are required in order for the recipient to know that they need to replace the set they have with the incoming set.
3.1.2.1.
In iTIP there is currently the possibility of adding an RRULE to an event using the ADD method, discussions about this should be brought to a public forum. See next topic for details on the ADD method.