From https://issues.kolab.org/show_bug.cgi?id=5445... if I have an iCal file with

BEGIN:VALARM
ACTION:AUDIO
TRIGGER:-PT15M
END:VALARM

and in python do:

from kolab.calendaring import EventCal
event = EventCal()
success = event.fromICal(ical)

it works, but if I then try to generate XML with:

event_xml = kolabformat.writeEvent(event)
error = kolabformat.error()

I got error: Failed to parse calendar! Everything works if I add ATTACH property, but according to RFC 5545 it is not required.