70 ILCS 410/15.4
The bonds shall bear interest at a rate not to exceed the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract, payable annually or semiannually and shall mature within the period of usefulness of the project as determined by the board, but in no event, exceeding 40 years.
Each such bond shall be sold in such manner and upon such terms as the board shall determine. If any such bond is issued to bear interest at the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract, it shall be sold for not less than par and accrued interest. If it is issued to bear interest at a rate of less than the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract, the minimum price at which it may be sold shall be such that the interest cost to the district of the proceeds of the bond shall not exceed the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract, computed to maturity, according to the standard table of bond values.
With respect to instruments for the payment of money issued under this Section either before, on, or after the effective date of this amendatory Act of 1989, it is and always has been the intention of the General Assembly (i) that the Omnibus Bond Acts are and always have been supplementary grants of power to issue instruments in accordance with the Omnibus Bond Acts, regardless of any provision of this Act that may appear to be or to have been more restrictive than those Acts, (ii) that the provisions of this Section are not a limitation on the supplementary authority granted by the Omnibus Bond Acts, and (iii) that instruments issued under this Section within the supplementary authority granted by the Omnibus Bond Acts are not invalid because of any provision of this Act that may appear to be or to have been more restrictive than those Acts.
70 ILCS 410/15.4