When DTSTART in VEVENTs with RRULE is modified, update RECURRENCE-ID in all the remaining components
I create an event, repeating every second week for four times, starting today at 14:00 UTC:
BEGIN:VCALENDAR
PRODID:-//Ximian//NONSGML Evolution Calendar//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:20211222T110707Z
DTEND:20211222T150000Z
DTSTAMP:20211213T173653Z
DTSTART:20211222T140000Z
LAST-MODIFIED:20211222T110815Z
RRULE;X-EVOLUTION-ENDDATE=20220202T140000Z:FREQ=WEEKLY;INTERVAL=2;
BYDAY=WE;COUNT=4
SEQUENCE:3
SUMMARY:Zzz
UID:aa06f594967e8abc3c468b1a1e7c2309831996ff
END:VEVENT
END:VCALENDAR
I chaange the instance on 5th January to start one hour later, and modify its caption:
BEGIN:VCALENDAR
PRODID:-//Ximian//NONSGML Evolution Calendar//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:20211222T110707Z
DTEND:20211222T150000Z
DTSTAMP:20211213T173653Z
DTSTART:20211222T140000Z
LAST-MODIFIED:20211222T110815Z
RRULE;X-EVOLUTION-ENDDATE=20220202T140000Z:FREQ=WEEKLY;INTERVAL=2;
BYDAY=WE;COUNT=4
SEQUENCE:3
SUMMARY:Zzz
UID:aa06f594967e8abc3c468b1a1e7c2309831996ff
END:VEVENT
BEGIN:VEVENT
CREATED:20211222T110707Z
DTEND:20220105T140000Z
DTSTAMP:20211213T173653Z
DTSTART:20220105T130000Z
LAST-MODIFIED:20211222T110948Z
RECURRENCE-ID:20220105T140000Z
SEQUENCE:4
SUMMARY:Yyy
UID:aa06f594967e8abc3c468b1a1e7c2309831996ff
END:VEVENT
END:VCALENDAR
I open the first instance, and change the start from 14h to 10h. On saving I tell Evolution to update all instances. By “All instances” I mean without the exception on 5th January. Evolution uploads:
BEGIN:VCALENDAR
PRODID:-//Ximian//NONSGML Evolution Calendar//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:20211222T110707Z
DTEND:20211222T110000Z
DTSTAMP:20211213T173653Z
DTSTART:20211222T100000Z
LAST-MODIFIED:20211222T111113Z
RRULE;X-EVOLUTION-ENDDATE=20220202T100000Z:FREQ=WEEKLY;INTERVAL=2;
BYDAY=WE;COUNT=4
SEQUENCE:4
SUMMARY:Zzz
UID:aa06f594967e8abc3c468b1a1e7c2309831996ff
END:VEVENT
BEGIN:VEVENT
CREATED:20211222T110707Z
DTEND:20220105T140000Z
DTSTAMP:20211213T173653Z
DTSTART:20220105T130000Z
LAST-MODIFIED:20211222T110948Z
RECURRENCE-ID:20220105T140000Z
SEQUENCE:4
SUMMARY:Yyy
UID:aa06f594967e8abc3c468b1a1e7c2309831996ff
END:VEVENT
END:VCALENDAR
As can be seen, the RECURRENCE-ID does not match any instance of DTSTART+RRULE from the primary event and thus does not replace any instance anymore. Evolution shows now the Zzz event on 22nd Dec, 5th and 19th January, and 2nd Febrary. In addition it shows the exception Yyy again on 5th January. Making in total 5 repetitions, with two repetitions on 5th January.
When I change the Zzz component to start again on 14h, Evolution uploads three components:
BEGIN:VCALENDAR
PRODID:-//Ximian//NONSGML Evolution Calendar//EN
VERSION:2.0
BEGIN:VEVENT
CREATED:20211222T110707Z
DTEND:20211222T110000Z
DTSTAMP:20211213T173653Z
DTSTART:20211222T100000Z
LAST-MODIFIED:20211222T111113Z
RRULE;X-EVOLUTION-ENDDATE=20220202T100000Z:FREQ=WEEKLY;INTERVAL=2;
BYDAY=WE;COUNT=4
SEQUENCE:4
SUMMARY:Zzz
UID:aa06f594967e8abc3c468b1a1e7c2309831996ff
END:VEVENT
BEGIN:VEVENT
CREATED:20211222T110707Z
DTEND:20211222T150000Z
DTSTAMP:20211213T173653Z
DTSTART:20211222T140000Z
LAST-MODIFIED:20211222T111601Z
RECURRENCE-ID:20211222T100000Z
SEQUENCE:5
SUMMARY:Zzz
UID:aa06f594967e8abc3c468b1a1e7c2309831996ff
END:VEVENT
BEGIN:VEVENT
CREATED:20211222T110707Z
DTEND:20220105T140000Z
DTSTAMP:20211213T173653Z
DTSTART:20220105T130000Z
LAST-MODIFIED:20211222T110948Z
RECURRENCE-ID:20220105T140000Z
SEQUENCE:4
SUMMARY:Yyy
UID:aa06f594967e8abc3c468b1a1e7c2309831996ff
END:VEVENT
END:VCALENDAR