What do these headers mean, exactly

[eluser]deco10[/eluser]
Can somebody shed some light on what these actually mean? They're in the documentation for set_header()

$this->output->set_header('Last-Modified: '.gmdate('D, d M Y H:i', $last_update).' GMT');
$this->output->set_header("Cache-Control: no-store, no-cache, must-revalidate");
$this->output->set_header("Cache-Control: post-check=0, pre-check=0");
$this->output->set_header("Pragma: no-cache");

[eluser]wabu[/eluser]
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html

Also cures insomnia.

[eluser]Phil Sturgeon[/eluser]
Stops caching and allows you to set a date where it was last modified.

It's all written in English, and Google will fill any knowledge gaps.

[eluser]krif[/eluser]
By the way, here is an interesting post on MSDN that says that setting pre-check and post-check both to 0 doesn't have the desired effect of not caching a page. You should at least set

Code:

Cache-Control: post-check=0; pre-check=1

Read the details here:

http://blogs.msdn.com/ieinternals/archiv...tives.aspx