Change html of category box

[Guest fnak]

I'm trying to do something as trivial as change categories with sub-categories in the category box to be rendered with "span" tags instead of "a" tags...

Something like this:

<ul>

<li><span>test</span><ul><li><a>test</a></li></ul></li>

<li><a>test</a></li>

</ul>

But after spending hours looking over the code I can't figure out how this .... works. Where is the documentation? I can't find anything that explains the relationship between the php code and the templating system, how does it work, how does it cache, how can I effectively use it?