Texas Transportation Code - TRANSP § 317.154. Terms of Issuance of Revenue Refunding Bonds

(1) be combined with new or original revenue bonds into one series or issue;

(2) be issued to refund bonds of more than one series or issue;

(3) combine the pledges securing the bonds to be refunded to secure the revenue refunding bonds;  or

(4) be secured by a pledge of other or additional net revenue.