module Time_ns : sig ... endmodule Zone : sig ... endmodule type Gen = sig ... endmodule type Gen_set = sig ... endmodule type S = sig ... endmodule type S1 = sig ... endmodule type S_time = sig ... endmodule type Interval = sig ... endModule for simple closed intervals over arbitrary types. Used by calling the Make functor with a type that satisfies Comparable (for correctly ordering elements).