Powder diffraction is the mostly widely used crystallographic method with applications spanning all aspects of structural science. This new volume of *International Tables* covers all aspects of the technique with over 50 chapters written by experts in the field.

The volume contains seven parts:

- Part 1 provides an introduction to the principles of powder diffraction.
- Part 2 covers instrumentation for laboratory X-ray studies, synchrotron, neutron and electron diffraction, 2D diffraction, and special environments (temperature, pressure, magnetic fields, reaction cells). Sample preparation is also covered.
- Part 3 describes the different methodologies used in powder diffraction.
- Part 4 covers structure determination and validation.
- Part 5 discusses defects, texture and microstructure: stress and strain, grain size and thin films.
- Part 6 provides a useful review of available software.
- Part 7 describes applications to many areas of industrial and academic importance including: macromolecules, zeolites, mining, ceramics, cement, forensic science, archaeology and pharmaceuticals. Both the theory and applications are discussed.

Part 1 of the volume includes chapters on groups, crystallographic and space-group symmetry, descriptions of space groups, coordinate-system transformations and methods of space-group determination. The final chapter provides a useful introduction to topics treated in more depth in Volumes A1 and E of the series. The chapters in this part have been written with teaching in mind.

Part 2 of the volume presents the diagrams and tables of plane- and space-group data. The layout of the tables of data, the symbols used in the diagrams and the classification of the space groups are explained in a useful guide.

Part 3 treats more advanced topics on space-group symmetry, and covers crystal lattices, point groups and crystal classes, space-group symbols and their use, lattice complexes, normalizers of space groups, and magnetic subperiodic groups and magnetic space groups.

There are eight new chapters in this sixth edition of Volume A, and five chapters have been revised. The layout of the space-group tables has been simplified as the sub- and supergroup data are now available in Volume A1, and there are new general-position diagrams for the cubic space groups. Additional diagrams showing tilted, perspective views of some of the more complex cubic space groups are also provided.

The second edition of Volume D was published in September 2014 (ISBN 978-1-118-76229-5) and may be ordered from Wiley.

This edition of Volume D features a new chapter (Chapter 1.11) on the tensorial properties of local crystal susceptibilities, by V. E. Dmitrienko, A. Kirfel and E. N. Ovchinnikova. This chapter describes the symmetry and physical phenomena that allow and restrict forbidden reflections excited at radiation energies close to the X-ray absorption edges of atoms. Reflections caused by magnetic scattering are also discussed.

In Part 1, Chapters 1.1 (an introduction to the properties of tensors), 1.2 (on representations of crystallographic groups), 1.3 (elastic properties), 1.5 (magnetic properties) and 1.10 (on tensors in quasiperiodic structures) have been revised. In particular, Chapter 1.5 features a new section on multiferroics by M. Kenzelmann.

Chapter 3.3 on twinning of crystals has been updated and new sections on the effect of twinning in reciprocal space and on the relations between twinning and domain structure have been added. Chapter 3.4 on domain structures has also been updated.

All known errors in the first edition have also been corrected.

The second edition of Volume F was published in January 2012 (ISBN 978-0-470-66078-2) and may be ordered from Wiley. It contains nineteen new articles and many articles from the first edition have been revised. The new articles cover topics such as standard definitions for quality indicators, expression of membrane proteins, protein engineering, high-throughput crystallography, imaging of whole cells, radiation damage, merohedral twinning, low resolution *ab initio* phasing, robotic crystal loading and halogen interactions in biological crystal structures. There are also new articles on relevant software, including software for electron microscopy. These enhancements will ensure that Volume F continues to be a key reference for macromolecular crystallographers and structural biologists.

The second edition of Volume E was published in 2010 (ISBN 978-0-470-68672-0) and may be ordered from Wiley. Typographical errors have been corrected and additional information has been included in the multi-page, multi-column comparison tables of notations for the seven crystallographic frieze-group types (two-dimensional groups with one-dimensional translations), the 75 crystallographic rod-group types (three-dimensional groups with one-dimensional translations) and the 80 crystallographic layer-group types (three-dimensional groups with two-dimensional translations) to improve ease of use. In the symmetry-operations section for each group table, the Seitz notation of each symmetry operation has been added below the corresponding international notation.

The second edition of Volume A1 was published in 2010 (ISBN 978-0-470-66079-9) and may be ordered from Wiley. All errors detected in the first edition have been corrected and local improvements have been introduced.

Part 1 deals with group-theoretical aspects of space groups, group-subgroup relations and the underlying mathematical background. In the new edition, the mathematical background has been extended to the theory of the minimal supergroups of the space groups. A new section has been added which gives instructions on how to build trees of group-subgroup relations for crystal structures that can be derived from a high-symmetry structure type (aristotype). Trees of this kind are useful to show crystallographic relations between crystal-structure types and between the polymorphic forms of a compound. A new section on the Bilbao Crystallographic Server has also been added with descriptions of the databases and computer programs that are related to the subjects of the volume.

Part 2 contains complete listings of all maximal subgroups for each space group, including their general positions or their generators, their conjugacy relations and transformations to conventional settings. The new edition contains a detailed discussion of the listed supergroup data, and a procedure for the complete derivation of the minimal supergroups from the listed (complete) data on maximal subgroups has been added.

Part 3 lists the relations between the Wyckoff positions for every maximal subgroup of every space group, including the cell transformations and coordinate transformations. In both Parts 2 and 3, the infinitely many isomorphic subgroups have been included in a parametrized form.

The main purpose of the new sixth edition of what was previously known as the Brief Teaching Edition of Volume A will be to provide an introduction to the space-group data in Volumes A and A1. This edition is designed more specifically for people new to the field of crystallographic symmetry and will also include introductions to Vol. E of *International Tables*, to magnetic space groups and to the Symmetry Database.