From Online Dictionary of Crystallography
Classes de Laue (Fr); Laue Klassen (Ge); Clases de Laue (Sp); Classi di Laue (It); ラウエ結晶類(Ja).
The Laue classes are eleven geometric crystal classes containing centrosymmetric crystallographic types of point groups and their subgroups. When absorption is negligible and Friedel's law applies, it is impossible to distinguish by diffraction between a centrosymmetric point group and one of its non-centrosymmetric subgroups; only point groups belonging to different Laue classes can then be distinguished.
|Laue classes||Non-centrosymmetric groups|
in the same Laue class
|4/mmm||422, , 42m|
|6/mmm||622, , 62m|
Chapter 3.1 of International Tables of Crystallography, Section A
Chapter 2.4 of International Tables of Crystallography, Section D