signature PoD =
    sig
	type term   = Term.term
	type thm    = Thm.thm
	type fixity = Term.fixity;
	    
	val newTypeDefinition : string -> thm -> thm
	val newSpecification  : string -> (string*fixity) list -> thm -> thm
	val newDefinition     : term frag list -> string -> fixity -> thm
        val get_def_names     : 'a frag list -> string * string
    end
