Previous work on electron-diffraction symmetries is extended to include Kossel-Möllenstedt patterns, Kikuchi patterns and electron-channelling (Coates) patterns.

Electron diffraction intensities are not simply related to the corresponding structure factors except in the case of `dynamical extinctions'. These extinctions, explained by Gjønnes & Moodie [Acta Cryst. (1965), 19, 65-67], occur for reflections that are kinematically forbidden - thus the resulting intensity is zero. If it was possible to find conditions when `dynamical extinction' occurs for reflections that are not forbidden, it would be possible to use electron diffraction intensities for the determination of structure factors in a simple way. Unfortunately, it can be shown that this is not possible.