Appended Link In Urls a different kind of appended links from get variables

I was viewing this site http://forums.xisto.com/no_longer_exists/ and noticed they use links in the address bar in an uncommon way. Is this kind of linking done by the CMS or web server level? I am trying to figured how this works and what language supports it. I have noticed all the pages seem to end in .html but are preceded by index.php first. I did not know this type of linking was valid as compared to the common appended get variables method. There are even some cases where deep linking is done with two or more parent folders. Any one familiar with this?

Interesting site.

Any one familiar with this?

Yeah, i use it on my website (except i don't end it in ".html"). It's a built-in feature of PHP, which helps save resources that would normally be wasted by mod_rewrite. What it is doing in the background is passing arguments to the PHP script as if it were a CLI script. I should mention it is search engine friendly.
Here's how you can implement it:

$file = substr($HTTP_SERVER_VARS['PATH_INFO'], 1);

If you have a URL like /index.php/html/1, you could use it like:

list($category, $page) = explode("/", substr($HTTP_SERVER_VARS['PATH_INFO'], 1));