Using COUNT to create unique anchors

I'm recursively going through my XML file to create a table of contents
for a document. I want to be able to link each item on the TOC to the
proper anchor later on the page.

So, I end up with something like this:

1. link 1
2. link 2
   2.1 link 2.1
   2.2 link 2.2
3. link 3

Link1 TITLE + CONTENT...
Link2 TITLE + CONTENT...
    link 2.1 TITLE + CONTENT...
    link 2.2 TITLE + CONTENT...
Link2 TITLE + CONTENT...

So, for each node, I need to generate a unique anchor to link to.

I could grab the number element and/or title element, but there's no
guarantee that they are all individually unique, so I'd rather rely on
just numbering them myself in the transformation.