driveway.com / cadaver interop

In the response to a PROPFIND with the following body:

<?xml version="1.0"?>
<propfind xmlns="DAV:">
  <prop><getcontentlength/><getlastmodified/><resourcetype/></prop>
</propfind>

the driveway.com server will include the DAV:supportedlock element for
non-collection resources, which seems wrong, although I can't find
anywhere in 2518 which actually says so. There should be some kind of
requirement that servers only return the *requested* properties for this
type of PROPFIND requests, shouldn't there? A MUST requirement would be
nice.

joe