POSIX systems actually have their own approach with "locales" and I it predates Unicode and ICU. Unfortunately, for a long time, POSIX system were uncommon on

POSIX systems actually have their own approach with "locales" and I it predates Unicode and ICU. Unfortunately, for a long time, POSIX system were uncommon on desktops, and most Unices do not provide a clean way to extend it from userland (though I believe GNU libc does).