public static function mimeToExt($type)
    {
        if (empty($type)) {
            return false;
        }

        if (($key = array_search($type, self::_getMimeExtensionMap())) === false) {
            list($major, $minor) = explode('/', $type);
            if ($major == 'x-extension') {
                return $minor;
            }
            if (strpos($minor, 'x-') === 0) {
                return substr($minor, 2);
            }
            return false;
        }

        return $key;
    }