The Default Locale
Methods in the Internationalization Module that accept a named locale to tailor their behavior to a specific locale use the current default locale if no locale is specified.
The current default locale is set at startup time to some system-specific value. On Windows, for example, the system default locale is set at installation, but can be changed in the Control Panel. On POSIX systems, the environment variable LANG and the LC_* variables are used to specify the default locale.
In the Internationalization Module, the current default locale may also be set programmatically using the static method RWULocale::setDefault().