In all legal documents we work with, "legal numbering" is like 1.2.1.3. Here's CSS for that:
http://lane.net.nz/blog/dave/creating-legal-list-numbering-o...
For your Digits, Roman Numerals, and Alpha numbering (mixed symbols), here's CSS for that:
http://css.wikidot.com/cssnippet:easy-outline
Use Markdown to make your list's HTML, use CSS to style it.