Problems with CalDAV and expand

[SimonRev]

Writing a CalDAV client to work with Zimbra and can't seem to get the expand element to work right.

According to the RFC, specifying the expand element should force Zimbra to return individual instances of recurring meetings for a time range and NOT return recurrence rules and the like (Calendaring Extensions to WebDAV (CalDAV)).

However, by taking the example from the RFC (Calendaring Extensions to WebDAV (CalDAV)) and modifying the dates, Zimbra simply returns the base recurrence rules for meetings that overlap that time and any exceptions. Specifically, I use this request:

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns="DAV:"
xmlns:C="urn:ietfarams:xml:ns:caldav">
<Drop>
<C:calendar-data>
<C:expand start="20080210T000000Z"
end="20080217T000000Z"/>
</C:calendar-data>
</Drop>
<C:filter>
<C:comp-filter name="VCALENDAR">
<C:comp-filter name="VEVENT">
<C:time-range start="20080210T000000Z"
end="20080217T000000Z"/>
</C:comp-filter>
</C:comp-filter>
</C:filter>
</C:calendar-query>

And the return result seems to violate the RFC by returning items such as RRULE which are explicitly forbidden, and by failing to expand the events into individual event instances.

Anyone else seen this or have any ideas?