Jeni's Musings

Regarding readability, how about:

  <pro;syn;title>

And

  <lab;1;rng>This <lab;2;rng>is some</lab;1;rng> text.</lab;2;rng>

Numeric labels do not have their own hierarchy, they are just syntactic aid to be able to match start and end tags. One could imagine that overlapping nodes are just siblings which happen to share some child nodes. It certainly is a different way of thinking than XCONCUR, I only used its syntax as starting point.