The preparation of Volume D has progressed steadily during the triennium. The few manuscripts still missing are expected to be delivered during the first half of 1999. The manuscripts, which were already in the hands of the Editor, were updated by their authors during 1998, and the whole volume will be sent to the Technical Editor in July 1999, even if one or two manuscripts are still outstanding. Volume D will include two accompanying software packages on a CD ROM. The first, dealing with tensors and irreducible representations, calculates representations of finite three-dimensional point groups and the components of invariant tensors in arbitrary dimension, of arbitrary rank, and with arbitrary permutation symmetry of the indices under the action of a three-dimensional crystallographic point group. The second, dealing with phase transitions, will give tables for equitranslational phase transitions, and for tensor properties at any group—subgroup phase transition: spontaneous tensor components, up to rank four, that appear in the distorted phase and non-zero tensor components that are the same in both phases.

Two meetings took place, the first in Nijmegen, The Netherlands, in February 1997 and the second in Prague, Czech Republic, in January 1998, in order to define and coordinate the contents of the two software packages. Alpha versions have been produced and tested. A beta version of the CD ROM including the two packages and a presentation page prepared by the IUCr Research and Development Officer should be ready for distribution in the spring of 1999.

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[1996] [2002] IUCr Triennial Report: Volume D. *Physical Properties of Crystals*

Updated 6th June 1999

**Copyright © 1999 International Union of Crystallography**