Bonds secured solely by a pledge of project revenue:
(1) are not a debt of the county issuing the bonds but are solely a charge on project revenue;
(2) may not be considered in determining the power of the county to issue for any purpose bonds payable in whole or in part from taxes; and
(3) must state: "The holder hereof shall never have the right to demand payment of this obligation out of any funds raised or to be raised by taxation."