WordPress at a glance
filter is not described

theme_locale filter-hook . WP 3.0.0

Filters a theme's locale.

Usage

add_filter( 'theme_locale', 'filter_function_name_3648', 10, 2 );
function filter_function_name_3648( $locale, $domain ){
	// filter...

	return $locale;
}
$locale(string)
The theme's current locale.
$domain(string)
Text domain. Unique identifier for retrieving translated strings.

Where the hook is called

load_theme_textdomain()
wp-includes/l10n.php 835
$locale = apply_filters( 'theme_locale', determine_locale(), $domain );

Where the hook is used (in WP core)

Does not used.