header("не кэшируй, гад!");
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // Datum aus Vergangenheit
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");