"This property specifies the date and time that the calendar information was created by the calendar user agent in the calendar store. Note: This is analogous to the creation date and time for a file in the file system."
"The property specifies the date and time that the information associated with the calendar component was last revised in the calendar store. Note: This is analogous to the modification date and time for a file in the file system."
"This property is used in conjunction with the "UID" and "SEQUENCE" property to identify a specific instance of a recurring "VEVENT", "VTODO" or "VJOURNAL" calendar component. The property value is the effective value of the "DTSTART" property of the recurrence instance."
"This property specifies the identifier corresponding to the highest version number or the minimum and maximum range of the iCalendar specification that is required in order to interpret the iCalendar object."