short communications
Owing to a printer's error, pages 359 and 360 of this article [Guss, Messer, Costello, Hardy & Kumar (1997). Acta Cryst. D53, 355-363Acta Cryst. D53, 355-363] were incorrectly numbered and thus printed in the wrong order. Revised offprints for this paper are available through the Managing Editor, International Union of Crystallography, 5 Abbey Square, Chester CH 1 2HU, England.