public function header()
{
$base = system::OLIV_PROTOCOL() . system::OLIV_HOST() . system::OLIV_BASE();
$o = "<meta http-equiv='Content-Type' content='text/html; charset=UTF-8'>";
// set page to utf-8
$o .= "<base href='{$base}'>";
// link base referenz
$o .= "<title>" . status::oliv_page() . "</title>";
// page title in browser
$o .= "<link href='" . OLIVImage::_(system::OLIV_ICON()) . "' type='image/x-icon' rel='shortcut icon'>";
// icon in browser
return $o;
}