... or properties may be treated as one improvement or property . . . . [ N.J.S.A. 40A:2-12(a)(1) (emphasis added).] The statute only mandates that 'certain ... 75 N.J. 163, 170 (1977) (emphasis in original) (quoting N.J.S.A. 40A:2-12); see also Matlack v. Bd. of Chosen Freeholders, 191 N ... calculate the period of usefulness. We agree with this reasoning. N.J.S.A. 40A:2-12(b) states that a bond ordinance must contain 'a determination ...