[OS X Emacs] AppleLocale ?

Wed May 24 22:45:15 EDT 2017

In Changelog.12 there is:

2005-04-14  YAMAMOTO Mitsuharu  <mituharu at math.s.chiba-u.ac.jp>

	* international/mule-cmds.el (set-locale-environment): On Mac OS,
	use preferences AppleLocale and AppleLanguages, and variable
	mac-system-locale for default locale.  On Mac OS Classic, use
	mac-system-coding-system for default coding systems.

There is no further references to mac-system-locale in the other changelogs but it looks like mule-cmds.el does not define it and there does not seem to be any place in the Emacs code that refers to AppleLocale or AppleLanguages.

Am I missing something ?

How does Emacs get the environment language set in System > Preferences ?

Jean-Christophe 