55 ILCS 5/6-4004

The bonds shall be executed by such officials as may be provided in the resolution authorizing the issue. The bonds may be made registerable as to principal and may be made callable on any interest payment date at par and accrued interest after notice has been given at the time and in the manner provided in the resolution. The bonds shall remain valid even though one or more of the officers executing the bonds ceases to hold office before the bonds are delivered.