>>Request

PUT /user/fred/readcalendar/event1.ics HTTP/1.1
Host: example.com
Content-Type: application/xml+calendar; charset="utf-8"
Content-Length: ?

<?xml version="1.0" encoding="utf-8" ?>
<icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
  <vcalendar>
  ...
  </vcalendar>
</icalendar>

>>Response

HTTP/1.1 403 Forbidden
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8"
  xmlns:D="DAV:"
  xmlns:CW="http://docs.oasis-open.org/ns/wscal/calws" ?>
<CW:error>
  <CW:target-exists/>
  <CW:description>Target of update must exist</C:description>
</CW:error>