A segment description for the unique set of reflections in non-centrosymmetric crystal classes

The segment description of the unique set of reflections of Gabe [In Crystallographic Computing, edited by F.R. Ahmed. Copenhagen: Munksgaard (1969)] and Le Page & Gabe [J. Appl. Cryst. (1979). 12, 464-466] has been extended to the non-centrosymmetric crystal classes. To the reflections generated by the unique set of the Laue group are added the anti-reflections generated by a set of anti-segments. These anti-segments are defined by the same lattice rows as those of the corresponding Laue group but their origins are shifted to avoid generating anti-reflections in any centrosymmetric section of reciprocal space.