public static function getUnknownActionName($type)
    {
        if (empty(self::$defaultActionNameWhenNotDefined)) {
            self::$defaultActionNameWhenNotDefined = Piwik::translate('General_NotDefined', Piwik::translate('Actions_ColumnPageName'));
            self::$defaultActionUrlWhenNotDefined = Piwik::translate('General_NotDefined', Piwik::translate('Actions_ColumnPageURL'));
        }
        if ($type == Action::TYPE_PAGE_TITLE) {
            return self::$defaultActionNameWhenNotDefined;
        }
        return self::$defaultActionUrlWhenNotDefined;
    }