Here's a partially marked-up view of Si down the zone. The (000) spot in the single-crystal diffraction pattern at right is also known as "the unscattered beam" or "the DC i.e. zero-frequency peak". In the direct-space image at left, the 0.543 line denotes one edge of the cubic unit cell, while the 0.235 line marks the tetrahedral nearest-neighbor distance between two adjacent silicon atoms.