DAV/Resourcetypes/collection

A DAV 'collection' is the basic equivalent of a 'Folder' or 'Directory' on regular filesystems.

Within the various DAV specifications a 'Collection' may additionally be one or more of the following Resourcetypes:
 * DAV principal defined in
 * CalDAV calendar defined in
 * CalDAV schedule-calendar
 * CalDAV schedule-inbox
 * CalDAV schedule-outbox

Restrictions

 * 1) The CalDAV specification states specifically that calendar collections may not contain children which are collections.
 * 2) Just in case you missed that, a schedule-outbox MUST NOT be a child of a calendar collection.