ABSTRACT
The principles for the plotting of poles on stereographic projections are nevertheless identical for any lattice. However, the cubic system exhibits extraordinary symmetry so angular relationships on the stereographic projection are not dependent on the lattice parameter. This is not the case for other lattices with lesser symmetry, the stereograms of which not only appear different from a distance, but for the same lattice type, the angular positions become dependent on the lattice parameters. This chapter discusses the Miller–Bravais four-index system which eliminates the ambiguity but requires additional work to ensure that the Weiss zone rule is satisfied. Whether the intellectual cost of the four-index system over the usual three-index notation is justified by its elegance is a matter of taste. The hexagonal system poses a particular problem of communication because of the nature of the special symmetry of the hexad.
