(* Rebinding and respecification as constructors of the identifiers *	true, false, it, nil, ::, ref  * is no longer permitted.  *) datatype t = true;datatype t = false;datatype t = it;datatype t = nil;datatype t = op ::;datatype t = ref; datatype t = true of int;datatype t = false of int;datatype t = it of int;datatype t = nil of int;datatype t = op :: of int;datatype t = ref of int;  exception true;exception false;exception it;exception nil;exception op ::;exception ref; exception true = Div;exception false = Div;exception it = Div;exception nil = Div;exception op :: = Div;exception ref = Div; exception true of int;exception false of int;exception it of int;exception nil of int;exception op :: of int;exception ref of int;  abstype t = true of int with end;abstype t = false of int with end;abstype t = it of int with end;abstype t = nil of int with end;abstype t = op :: of int with end;abstype t = ref of int with end;