Gets the Appointment object that defines the recurrence criteria for this Appointment object. If this appointment is a not member of a recurrence, or is itself a root appointment, null is returned.
If an appointment is recurring (see the IsRecurring property) it represents an occurrence in the series that is started and defined by a specific pattern appointment. Use the ParentRecurrence property to obtain the pattern of the current appointment. A pattern appointment can be recognized by its RecurrenceState property set to the RecurrenceStateEnum.Master value. The recurrence information defined by the pattern appointment can be accessed via the RecurrencePattern property of the appointment.