Legacy UNTIL Concerns

If the PRODID property (see section indicates that a version of the MIMEDIR between 1 and 11 (inclusive) generated the iCalendar file and if the UNTIL recurrence part is specified with a trailing 'Z', it SHOULD NOT<311> be treated as a UTC Date-time. Instead, only the year, month, and day of the Date-time SHOULD<312> be retained, and the UNTIL recurrence part SHOULD<313> be interpreted as 11:59 P.M. of that day (in the time zone specified by PidLidTimeZoneStruct).