I don't think there is a need to bring up "semantics" here, and the only reasonably defined semantics that I know for the term "almost all" would be from set th

I don't think there is a need to bring up "semantics" here, and the only reasonably defined semantics that I know for the term "almost all" would be from set theory where that is a useless term without an infinite set to measure against. Common sense anyway would suggest that "almost every" is distinct from "many, but also many not", and the latter is what I think would be a better fit here. The intention behind my comment (and I thought it was clear without any "semantics" discussion required) was to show that there is no need for the POSIX layer to be included as part of ISO C. POSIX is just a "platform layer" (for all I know), meaning that it is much closer to a "library" than a "runtime". I don't see a need to bundle it tightly with the language. Heck, why did I even bring up Windows as a counterexample, when there are probably a lot of more-or-less ISO C conforming compilers for microcontroller platforms that could never support POSIX.