Recognition and use of systematically aberrant phase relationships. I: Erratum

In the paper by Britton & Dunitz [Acta Cryst. (1981), A37, 131-132] three errors have been printed. On p. 131, 2nd column, line 5: '-2' should be changed to '-3'; on p. 132, 1st column, line 6: 'one-third' should be changed to 'half'; p. 132, 2nd column, lines 2-3: 'relatively even deeper' should be changed to 'only slightly less deep'.