Twinning analyses in the X-ray theory

Commonly, expositions of twinning theory combine at least two di€erent kinds of observations: measurements of macroscopic deformation and those made using X-rays. I believe that there is some merit in considering the latter separately because, often, the two kinds do not mesh very well. Here, my aim is to elaborate this and to improve the twinning theory based on a theory of X-ray observations to be described