When creating documentation its always a good idea to start from this template and modify and add to it as you see fit, below is the wiki code and an actual rendering of what the template looks like.
Because of a wiki bug when you put % % % without spaces around the php code in the example below it causes it to still output the html code despite being in a <nowiki> tag. So when using the template remember to remove the spaces from the % % % on either side of the php code.
== Description ==
Enter a description of the function here.
== Parameters ==
{{Parameter|$name|cast|Description}}
{{Parameter|$name|cast|Description|optional|default value}}
== Return Values ==
; <tt>(cast)</tt> : description.
== Usage ==
% % %<?php function(); ?>% % %
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[[Category:WPMU]]
[[Category:WPMU Functions]]
Enter a description of the function here.
<?php function(); ?>