>>Request

POST /user/fred/readcalendar/?action=create HTTP/1.1
Host: example.com
Content-Type: text/text; charset="utf-8"
Content-Length: ?

This is not an xml calendar object

>>Response

HTTP/1.1 403 Forbidden
  <?xml version="1.0" encoding="utf-8"
    xmlns:D="DAV:"
    xmlns:C="urn:ietf:params:xml:ns:caldav" ?>
<D:error>
    <C:supported-calendar-data/>
    <D:description>Not an icalendar object</D:description>
</D:error>