Tenn. Code Ann. § 9-11-110

Except as hereinafter provided, the authority conferred by this chapter may be exercised at any time and from time to time, and the authorization of funding or refunding bonds by one (1) bond order shall not prevent the authorization of additional funding or refunding bonds by subsequent bond order or orders. One (1) resolution providing for the issuance of funding or refunding bonds may provide for the issuance of two (2) or more separate series of such bonds, and each series or class may have different terms and provisions from the others, and the bonds of each series or class may bear interest at different rates.