Bonds issued under this chapter may be secured by:(1) solely a pledge of revenues, in the manner and to the extent prescribed for a county by Chapter 284, Transportation Code;(2) a pledge of, and making the bonds payable from, an ad valorem tax authorized by Section 52(b), Article III, Texas Constitution;(3) designating a portion of the bonds to be secured solely by a pledge of revenues as provided by Subdivision (1) and a portion of the bonds to be secured by a pledge of an ad valorem tax as provided by Subdivision (2); or(4) a combination of the methods prescribed by Subdivisions (1) and (2) through which all of the bonds are to be supported and secured by a pledge of revenue and ad valorem tax, in the manner and to the extent prescribed for a county by Chapter 284, Transportation Code. Added by Acts 2005, 79th Leg., Ch. 729 (H.B. 2019), Sec. 1.04, eff. April 1, 2007.