Ranking among different issues.

All securities of the same issue or series shall, subject to the prior and superior rights of outstanding securities, claims and other obligations, have a prior, paramount and superior lien on the revenues pledged for the payment of the securities over and ahead of any lien thereagainst subsequently incurred of any other securities; provided, however, the resolution authorizing, or other instrument appertaining to, the issuance of any securities may provide for the subsequent authorization of bonds or other securities the lien for the payment of which on such revenues is on a parity with the lien thereon of the subject securities upon such conditions and subject to such limitations as said resolution or other instrument may provide.