Eia-310-d [2021] Page

The standard defines the center-to-center distance of the mounting holes. If you look at a server rack, you will see a repeating pattern of holes (usually three holes per "U" in a square pattern, or a continuous strip). EIA-310-D dictates the exact placement of these holes so that the "U" markings align perfectly. This modularity allows data center managers to calculate density with mathematical precision.