RECURID

Purpose: This property is used in conjunction with the "UID" and "SEQUENCE" properties to identify a specific instance of a recurring "VEVENT", "VTODO", or "VJOURNAL" calendar component. The property value is the original value of the "DTSTART" property of the recurrence instance, ie. a DATE or DATETIME value e.g. "20211101T160000". Must be null for non-recurring and original events from which recurring events are derived. Type: String