Pub. Util. Code, § 99332

Bonds of the same issue shall be equally secured by a pledge, charge, and lien upon the revenues specified in the resolution authorizing the issuance of the bonds, without priority for number, or date of bonds, of sale, of execution, or of delivery pursuant to this chapter and the resolution authorizing the issuance of the bonds; except that any county, with the consent of the transportation planning agency, may authorize the issuance of bonds of different series and may provide that the bonds in any series shall, to the extent and in the manner prescribed in the resolution, be subordinated and be junior in standing, with respect to the payment of principal and interest and the security thereof, to such other bonds as may be specified in the resolution.