During the last few decades, crystallography has become a wide and economically important field of science with many interesting applications in materials research, in different branches of physics, chemistry, geology, pharmacology, biochemistry, electronics, in many technological processes, machinery, heavy industry, etc. Twenty Nobel prizes awarded for achieve ments belonging to this. field only underline its distinction. Crystallo graphy has become a commonly used term, but - like a whale - it is much easier to recognize than to describe because of an extreme diversity of sub jects...