This page lists the Extension used and their Function
A list of all Extensions and their functions can be found at Special:Version.
One of the usages is in the Template:Openx where it calls a html file with the banner code.
Including a HTML snippets is done using a special tag, <htmlet>. For example, if you put this on a wiki page:
This will include the contents of the file foobar.html from the htmlet directory. If the snippet may change often, and you want those changes reflected on the wiki page right away, you can tell HTMLets to disable the parser cache for this page:
- <htmlet nocache="yes">foobar</htmlet>
The htmlet directory can be configured using $wgHTMLetsDirectory; it defaults to "$IP/htmlets", i.e. the directory htmlets in the installation root of MediaWiki; but note that if you follow the instructions given above for adding code to your LocalSettings.php file, the htmlet directory will be set to "$IP/extensions/HTMLets". $wgHTMLetsDirectory may also refer to a place on a webserver, for example, you can set it to http://localhost/htmlets/, if you provide htmlets in that location - note that the .html ending is enforced, query strings are not allowed in the htmlet's name.