This section lists what functionality is required of a CalDAV server. To advertise support for CalDAV, a server:
o MUST support iCalendar [RFC2445] as a media type for the calendar object resource format;
o MUST support WebDAV Class 1 [RFC2518] (note that [rfc2518bis] describes clarifications to [RFC2518] that aid interoperability);
o MUST support WebDAV ACL [RFC3744] with the additional privilege defined in Section 6.1 of this document;
o MUST support transport over TLS [RFC2246] as defined in [RFC2818] (note that [RFC2246] has been obsoleted by [RFC4346]);
o MUST support ETags [RFC2616] with additional requirements specified in Section 5.3.4 of this document;
o MUST support all calendaring reports defined in Section 7 of this document; and
o MUST advertise support on all calendar collections and calendar object resources for the calendaring reports in the DAV:supported- report-set property, as defined in Versioning Extensions to WebDAV [RFC3253].
In addition, a server:
o SHOULD support the MKCALENDAR method defined in Section 5.3.1 of this document.