Indiana Code Title 5. State and Local Administration § 5-1-14-16

(A) maintain substantially equal payments, in the aggregate, in any period in which the local issuing body pays the interest and principal on outstanding obligations;

(B) provide for the payment of principal on the obligations in amounts and at intervals that will produce an aggregate amount of principal payments greater than or equal to the aggregate amount that would otherwise be paid as of the same date;

(C) provide for level principal payments over the term of the obligations, in order to reduce total interest costs;

(D) with respect to obligations wholly or partially payable from tax increment revenues derived from property taxes, provide for the payment of principal and interest in varying amounts over the term of the obligations as necessary due to the variation in the amount of tax increment revenues available for those payments;  or

(E) provide for a repayment schedule that will result in the same or a lower amount of interest being paid on obligations that would be issued using nearly equal payment amounts.