The (currently revision EIA-310-D or updated as EIA/ECA-310-E ) is the fundamental specification for 19-inch rack cabinets, ensuring that hardware from different manufacturers fits into standard IT racks. Where to Find the Standard PDF
The current benchmark is (released in 1992), while the newer EIA/ECA-310-E (released in 2011) primarily updated terminology and grammatical consistency without changing core mechanical dimensions. Key Specifications of the EIA-310 Standard eia-310 standard pdf
If you are designing a server room or buying gear, you do not need to read the full legal text of the PDF. You only need to know the "Compliance Check": eia-310 standard pdf