A computer program has been written which generates a set of unique reflections within specified limits for a particular space group and given unit-cell dimensions for use with conventional or time-of-flight diffraction data. The set is output as a list of h, k, l, d spacing, scattering angle or time-of-flight, and multiplicity for all unique, non-equivalent symmetry-allowed reflections in order of decreasing d spacing. Symmetry conditions are normally generated from the space-group number, but they may be specified directly in the input data if non-standard settings are required, e.g. P21/a, or if additional special symmetry conditions are required. A further option is also provided to allow the suppression of specified reflection types.