PHP avoiding caches

My wife is re-starting Estudio-L and try to help her when php programing is neeeded, this few lines are useful and very reusable if you want to ensure that your clients are getting the lattest version of your web page

// Always send an expired date
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");

// Always send present moment as last modified
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");

// Normal headers for non chaching
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Pragma: no-cache"); // HTTP/1.0