function nocache() {
Header("Expires: Thu, 19 Feb 1998 13:24:18");
Header("Last-Modified: ".gmdate("D, d M Y H:i:s")." GMT");
Header("Cache-Control: no-cache, must-revalidate");
Header("Cache-Control: post-check=0,pre-check=0");
Header("Cache-Control: max-age=0");
Header("Pragma: no-cache");
}