The study of selected-area channelling pattern (SACP) degradation with deformation was performed using lines representing different sets of planes. It was established that the degradation of different lines on the SACP taken after a given deformation was not the same. It differs not only for lines from different sets of planes but also within the same type of line. The amount of relative line broadening depends on the position of a given plane with respect to the glide plane and direction. It tends toward a maximum for SACP lines from those planes perpendicular to the Burgers vector and a minimum for those parallel to that vector. It is proposed that at the beginning of the deformation process, while only. a few systems operate, this phenomenon is most pronounced because of glide anisotropy.