ARCH is mentioned several times in chapter about profiles, but not in ebuild env. At least portage provides it though, and lots of ebuilds use it. But I think we should decide if user can override this variable so easily (with arbitrary stuff, leading to bugs like bug 180410), or not...
Overriding it is useful for cross compiling.
with the advent of --config-root, it isnt that big of a deal then again, if we had automatic ARCH generation based on CHOST, this wouldnt be a problem ;) back to the point ... i'm not sure locking ARCH out of make.conf and in profiles is really the way to go, especially since we have no mechanism for doing so tell the ricers to stop being stupid
No need to mention it in PMS. It comes from profile make.defaults, which is already covered.