A scheduling Outbox collection is used as the target for busy time information requests, and to manage privileges that apply to outgoing scheduling requests.
A scheduling Outbox collection MUST report the DAV:collection and CALDAV:schedule-outbox XML elements in the value of the DAV: resourcetype property. The element type declaration for CALDAV: schedule-outbox is
<!ELEMENT schedule-outbox EMPTY>
A scheduling Outbox collection MUST NOT be a child (at any depth) of a calendar collection resource.
The following WebDAV properties specified in CalDAV "calendar-access" [RFC4791] MAY also be defined on scheduling Outbox collections and apply to scheduling messages submitted to the scheduling Outbox collection with the POST method:
The use of child resources in a scheduling Outbox collection is reserved for future revisions or extensions of this specification.
The following WebDAV property is defined on principal resources and used to locate the corresponding Outbox collection for the associated principal.