In the case of voted general obligation bonds to be payable from sources other than property taxes or special assessments pursuant to provision for payment from such other sources made by covenant or otherwise in the legislation authorizing the bonds, the interest may be determined as a variable rate or rates, which may change from time to time in accordance with a base, formula, or standard, including determination at whatever rate is required to sell the securities on the open market at par, or other floating rate interest structure, identified or approved by the taxing authority.
R.C. §133.26