Can’t tell if you’re joking, but a Request For Comments is effectively a proposal for how a process should be performed.
Some of them are eventually ratified as internet standards by the IETF.
Plenty of them remain useful as defacto standards even without formal acknowledgement.
.308 is 7.62, civilian measurement vs military (there’s actually implications related to pressures, sidewall thicknesses, machining tolerances, but yeah same same)