Html::displayBackLink PHP Метод

    static function displayBackLink()
    {
        if (isset($_SERVER['HTTP_REFERER'])) {
            echo "<a href='" . $_SERVER['HTTP_REFERER'] . "'>" . __('Back') . "</a>";
        } else {
            echo "<a href='javascript:history.back();'>" . __('Back') . "</a>";
        }
    }

--------------------------------------------------------------------------
*/
/** @file
* @brief
*/
include '../inc/includes.php';
Session::checkCentralAccess();
header("Content-Type: text/html; charset=UTF-8");
Html::header_nocache();
try {
    $ma = new MassiveAction($_POST, $_GET, 'process');
} catch (Exception $e) {
    Html::popHeader(__('Bulk modification error'), $_SERVER['PHP_SELF']);
    echo "<div class='center'><img src='" . $CFG_GLPI["root_doc"] . "/pics/warning.png' alt='" . __s('Warning') . "'><br><br>";
    echo "<span class='b'>" . $e->getMessage() . "</span><br>";
    Html::displayBackLink();
    echo "</div>";
    Html::popFooter();
    exit;
}
Html::popHeader(__('Bulk modification'), $_SERVER['PHP_SELF']);
$results = $ma->process();
$nbok = $results['ok'];
$nbko = $results['ko'];
$nbnoright = $results['noright'];
if ($nbok == 0) {
    $message = __('Failed operation');
} else {
    if ($nbnoright || $nbko) {
        $message = __('Operation performed partially successful');
    } else {