Locale Settings
From GeeklogWiki
Language Setting
The default language is set with the variable
$_CONF['language']='english_utf-8';
The allowed values are the names of the language files without the ".php".
If the users can change the language themselves is set in the Site Settings with the variable $_CONF['allow_user_language'].
The currently available languages are listed here. If your chosen language exists in different formats, or if you decide to run your system in several languages, please read the Language Tips And Tricks.