Further, both EBT's DynaText and SoftQuad's Explorer and Panorama products
can do highlighting across element boundaries.
BUT: I would not suggest using HyTime TREELOC notation in a web browser,
because this would require that all the browsers treat OMITTAG in the
same way. Currently, some browsers infer a <P> where others don't, I think,
and I don't consider it practical to try and deal with this, unfortunately.
I would like to suggest instead a hybrid approach.
 Allow an ID attribute on any container.
 Use a HyTime ladder to get to the containing element by ID where
 Use byte and/or (natural language) word counts within that container
 for multiple containers, e.g. the midst of one P unto the next, make
multiple 's within the .
This is what SoftQuad Panorama PRO and SoftQuad Explorer do.
The HyTime can go in a separate file.