EIA-310-D accommodates three common mounting hole types:
The standard defines the geometry of the holes on the vertical mounting rails: eia310d standard pdf
False. The standard allows round unthreaded, 10-32 threaded, and 12-24 threaded holes. It does not specify the modern "square hole" cage nut pattern. Square holes became popular through de facto industry adoption because they accept both metric (M6) and imperial (10-32) cage nuts. However, square holes are technically a later evolution (often referenced in EIA-310-E). EIA-310-D accommodates three common mounting hole types: The