BEGIN:VCALENDAR

BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200910T140000
DTEND;TZID=Europe/Berlin:20200910T150000
RRULE:FREQ=WEEKLY
SEQUENCE:0
SUMMARY:Base event
UID:series 1
END:VEVENT

BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20200917T140000
DTEND;TZID=Europe/Berlin:20200917T150000
RECURRENCE-ID:20200917T120000Z
SEQUENCE:1
SUMMARY:Modified event
UID:series 1
END:VEVENT


BEGIN:VEVENT
DTSTART;VALUE=DATE:20200907
DTEND;VALUE=DATE:20200908
RRULE:FREQ=WEEKLY
SEQUENCE:0
SUMMARY:Base event
UID:series 2
END:VEVENT

BEGIN:VEVENT
DTSTART;VALUE=DATE:20200914
DTEND;VALUE=DATE:20200915
RECURRENCE-ID:20200914
SEQUENCE:1
SUMMARY:Modified event 1
UID:series 2
END:VEVENT

BEGIN:VEVENT
DTSTART;VALUE=DATE:20200921
DTEND;VALUE=DATE:20200922
RECURRENCE-ID:20200921T000000Z
SEQUENCE:2
SUMMARY:Modified event 2
UID:series 2
END:VEVENT

END:VCALENDAR