PHP header file types

header('Content-type: application/pdf');
header('Location: http://ashokseenivas.blogspot.com/');
header("HTTP/1.0 404 Not Found");
header("Cache-Control: no-cache, must-revalidate");
header("Expires: Sun, 10 Aug 2008 05:00:00 GMT");
header('Content-type: text/xml');