Description:
------------
In http://php.net/header

// Date in the past
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
// always modified
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
// HTTP/1.1
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
// HTTP/1.0
header("Pragma: no-cache");


Despite disclaimer under this example I think useless headers should be removed.

last-modified is last resort in finding freshness of an object, and is not needed when expires and cache-control are present.

post-check and pre-check headers are always ignored when no-cache is specified. 

on most proxies no-cache and no-store make no difference, but the latter may impose extra restrictions in handling "sensitive information" and should not be abused just for any dynamic data.



Expected result:
----------------
header("Cache-Control: no-cache, must-revalidate");
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");

Actual result:
--------------
abuse of http by clueless copy'n'pasters.
backtraces to these lines in php docs :)