Bragg scattering, that is diffraction of inelastically scattered electrons, can lead to the formation of pairs of parallel lines in the diffraction pattern called Kikuchi lines. For each plane of atoms in the sample there exists a pair of parallel lines, rather like train lines. The various sets of Kikuchi lines intersect in diffraction space in a manner which represents the arrangement of crystal planes in real space. This is called a Kikuchi map. These lines can help an operator to tilt a crystal around to find different crystal planes. Kikuchi Patterns are a useful phenomenon to use when initially learning how to tilt crystals because they form regular intersecting lines over a zone axis.
This spot diffraction pattern shows Kikuchi lines on the left side of the pattern. This pattern is in the process of being tilted and not yet on the zone axis.