Busy time information of one or more calendar users can be determined by submitting a POST request targeted at the scheduling Outbox collection of the calendar user requesting the information (the "Organizer"). To accomplish this, the request body MUST contain a "VFREEBUSY" calendar component with the "METHOD" iCalendar property set to the value "REQUEST" as specified in Section 3.3.2 of iTIP [RFC5546]. The resource identified by the Request-URI MUST be a resource collection of type CALDAV:schedule-outbox (Section 2.1). The "ORGANIZER" property value in the "VFREEBUSY" component MUST match one of the calendar user addresses of the owner of the Outbox collection.
A response to a busy time request that indicates status for one or more calendar users MUST be an XML document with a CALDAV:schedule- response XML element as its root element. This element MUST contain one CALDAV:response element for each calendar user, with each such element in turn containing elements that indicate which calendar user they correspond to, the scheduling status for that calendar user, any error codes, and an optional description. For a successful busy time request, a CALDAV:calendar-data element is also present for each calendar user, containing the actual busy time information (i.e., an iCalendar "VFREEBUSY" component). See Section 10 for details on the child elements. See Appendix B.5 for an example busy time request and response.