PROCEDURE (t: Traffic) CheckUniqueName(): BOOLEAN;

        VAR
            teller1, teller2, lengte: INTEGER;
            node, node2, keepsafe, temp, temp2, keepsafe2: CircDLL.Node;
            pnode, pnode2: Airport.Airport;
    BEGIN
        node2 := t^.Planes^.GetFirstNode();
        node2 := node2^.NextNode();

        keepsafe := node2;

        node := t^.Planes^.GetFirstNode();
        lengte := t^.Planes^.GetLength();
        FOR teller1 := 1 TO lengte BY 1 DO
            FOR teller2 := 2 TO lengte BY 1 DO
                IF node(Airplane.Airplane)^.GetNumber() = node2(Airplane.Airplane)^.GetNumber() THEN
                    RETURN FALSE;
                END;
                node2 := node2^.NextNode();
            END;
            keepsafe := keepsafe^.NextNode();
            node2 := keepsafe;
            node := node^.NextNode();
        END;

        temp := t^.Ports^.GetFirstNode();
        temp := temp^.NextNode();
        pnode2 := temp(Airport.Airport);

        keepsafe2 := pnode2;

        temp2 := t^.Ports.GetFirstNode();
        pnode := temp2(Airport.Airport);
        lengte := t^.Ports^.GetLength();
        Out.String(pnode^.name); Out.String("="); Out.String(pnode2^.name); Out.Int(lengte,0);

        FOR teller1 := 1 TO lengte BY 1 DO
            FOR teller2 := 2 TO lengte BY 1 DO
                IF pnode^.name = pnode2^.name THEN (* TRAP WHEN Getters ARE USED @@@ *)
                    Out.String(pnode^.name); Out.String("="); Out.String(pnode2^.name);
                    RETURN FALSE;
                END;
                temp := temp^.NextNode();
                pnode2 := temp(Airport.Airport);
            END;
            temp2 := temp2^.NextNode();
            pnode := temp2(Airport.Airport);
            keepsafe2 := keepsafe2^.NextNode();
            pnode2 := keepsafe2(Airport.Airport);
            END;
        RETURN TRUE;
    END CheckUniqueName;
-------------------------------------------------
Output :

A=B3B=BInconsistent Netwerk.