After a few agonizing days of attempting to set up some very custom category displays for a client, we are posting the results here in the hopes it might prevent some other poor programmer from gaining the very same forehead dents we currently sport.

(Note: the following was accomplished in a MT 3.34 environment)

The objective: List subcategories for one single category in Movable Type.

The solution:

First, install Staggernation's FilterCategories plugin.

Second, set up your categories, subcategories, etc., then use this code to call them:

<MTTopLevelCategories>
<MTFilterCategories include="Category">
<ul>
<MTSubCategories>
<li>
<a href="<$MTCategoryArchiveLink $>">
<$MTCategoryLabel$>
</a>
</li>
</MTSubCategories>
</ul>
</MTFilterCategories>
</MTTopLevelCategories>

Adjust the display mechanism (ie. ul, li, etc.) as you like and there you go.