zones {
  [ zone_options ]
  zone_id {
    file "string";
    [ xfr-in remote_id [, remote_id, … ]; ]
    [ xfr-out remote_id [, remote_id, … ]; ]
    [ notify-in remote_id [, remote_id, … ]; ]
    [ notify-out remote_id [, remote_id, … ]; ]
    [ update-in remote_id [, remote_id, … ]; ]
    [ zone_options ]
  }
}

zone_options :=
  [ storage "string"; ]
  [ semantic-checks boolean; ]
  [ ixfr-from-differences boolean; ]
  [ disable-any boolean; ]
  [ notify-timeout integer; ]
  [ notify-retries integer; ]
  [ zonefile-sync ( integer | integer(s | m | h | d); ) ]
  [ ixfr-fslimit ( integer | integer(k | M | G) ); ]
  [ ixfr-from-differences boolean; ]
  [ dnssec-keydir "string"; ]
  [ dnssec-enable ( on | off ); ]
  [ signature-lifetime ( integer | integer(s | m | h | d); ) ]
  [ serial-policy ( increment | unixtime ); ]