Sure. I've seen, and designed DTD's where you use linking to get things like
overlapping regions (for example, for linking over an arbitrary region).
This
is *really* useful for markup of parallel aligned texts... you can build a
translation memory out of a linkbase.
I like parallel markup mostly because it is about the only consistent way
to have multiple overlapping tagging structures for single text. Namespaces,
architectural forms, etc. etc. all solve *part* of that problem, but not
the whole thing. It's kind of interesting, because an awful lot of document
processing software had been built with something akin to parallel markup...
so that would seem to show that it is also somewhat intuitive.
> FWIW, the separation of presentation from structure/content
> predates both CSS and Nelson's article by about a quarter of
> a century.
Absolutely right.