(a) Bonds constituting a junior lien on the net revenues may be issued unless prohibited by the bond order or the trust indenture.
(b) Parity bonds may be issued under conditions specified in the bond order or trust indenture.
(c) The county may issue bonds to refund outstanding bonds in the same manner that other bonds are issued under this subchapter.
(d) Refunding bonds issued under this section may be exchanged for previous bonds by the comptroller or may be sold. If the bonds are sold, the proceeds shall be applied to the payment of outstanding bonds.