+extern type serial;
+{{Domain zone serial numbers}}
+extern val serialAuto : serial;
+{{Whenever DNS data changes, choose a sensible serial number automatically.}
+extern val serialConst : int -> serial;
+{{Use this particular serial number.}}
+
+extern type soa;
+{{DNS start-of-authority record}}
+extern val soa : domain -> serial -> int -> int -> int -> int -> soa;
+
+extern type dnsKind;
+{{How should DNS for this domain be handled?}}
+extern val master : soa -> dnsKind;
+extern val slave : soa -> dnsKind;
+extern val noDns : dnsKind;
+
+extern val domain : domain -> Domain => [Root] {DNS : dnsKind, TTL : int};