- All recent Linux/*BSD distros and of course Mac OS X install
with UTF-8 locales by default. Most single-char NLS functions
don't work _at all_ with UTF-8 locales (see recent thread).
When viewed from POSIX land (as Lua does) Mac OS X does not install
with a UTF-8 locale by default. It doesn't set the LANG POSIX
environment variable nor any of the LC_* environment variables,
therefore when a POSIX app does a setlocale("") it still remains in
the C/POSIX locale.
Granted UTF-8 is used pretty ubiquitously throughout Mac OS X, but
you still need to select it explicitly from the POSIX world.