For some reason, when it comes to POSIX, I always have a hard time finding the full scoop.
Is there one somewhere in the POSIX docs?
Granted, the links given above point to older version of the docs. It is possible that the nomenclature has changed since then. (E.g., maybe what used to be called "mandatory utilities" are now called "required utilities", or "obligatory utilities", or "core utilities", etc.) Or maybe the mandatory/optional distinction has been dropped altogether? Clarifications welcome.