ICS files from Microsoft Outlook differ from those that were created by Gnome Evolution. (semicolons are used instead of colons at some position) Evolution --------- all day event: DTSTART;VALUE=DATE:20230908 DTEND;VALUE=DATE:20230909 appointment: DTSTART;TZID=/freeassociation.sourceforge.net/Continent/City: 20230909T090000 DTEND;TZID=/freeassociation.sourceforge.net/Continent/City: 20230909T093000 This includes the continent and city of the used time zone. "DESCRIPTION:" is an optional field.