Lists of each different type may be nested inside of each other, creating complex lists for indexes, menus, etc.
Each subsequent level is a list item of the parent list, and is created as follows:
<OL>
<LI> This is Item 1 of the main list
<UL>
<LI> This is Item 1 of the first level sub list
<LI> This is Item 2 of the first level sub list
</UL>
<LI> This is Item 2 of the main list
</OL>