SubCatIsFirst
The contents of this container tag will be displayed when the first category listed by a mt:SubCategories loop tag is reached.
<mt:SubCategories>
<mt:SubCatIsFirst>
<!-- do something -->
<mt:else>
<!-- do something else -->
</mt:SubCatIsFirst>
</mt:SubCategories>
Use mt:SubCatIsLast for conditioning content at the end of the loop.
Examples
See mt:SubCategories loop tag for more examples.