encodingparam = "ENCODING" "=" ( "8BIT" ; "8bit" text encoding is defined in [RFC2045] / "BASE64" ; "BASE64" binary encoding format is defined in [RFC4648] ) busytypevalue = "BUSY" / "BUSY-UNAVAILABLE" / "BUSY-TENTATIVE" / iana-token / x-name ; Default is "BUSY-UNAVAILABLE".