If Maemo 5 doesn't support .ics files, then how do people send/receive calendar invites with the N900? What calendar attachment types can it handle?

These attachments are standard .ics files:

Content-Type: text/calendar; name="meeting.ics"; method="REQUEST"
MIME-Version: 1.0

BEGIN:VCALENDAR
VERSION:2.0
PRODID://RESEARCH IN MOTION//BIS 3.0
METHOD:REQUEST
BEGIN:VEVENT
SEQUENCE:2
X-RIM-REVISION:0
SUMMARY:Someones bday party
LOCATION:Here and There
CLASS:PUBLIC
ATTENDEE;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;CN=Kurt Mobile mail:MAILTO:someuser@void.com
UID:XRIMCAL-604136724-668212949-8585328
DTSTART:20100131T200000Z
DTEND:20100201T000000Z
DTSTAMP:20100119T215045Z
ORGANIZER:MAILTO:void@void.com
BEGIN:VALARM
ACTIONISPLAY
TRIGGER;VALUE=DURATION:-P00DT00H15M00S
END:VALARM
END:VEVENT
END:VCALENDAR