This overlaps with previous discussions about notes and related items, but as I'm working through a snapshot document I'm realizing I'd really like to assign semantics to the tagged fragments. In other words, rather than to just have a generic "highlight" to be able to say exactly what I'm highlighting.

For example, I'm working on a legal opinion at the moment, and I highlight a fragment where the court is referring to some previous case; would like to be able to tag it with some property, and maybe even to be internally use something like eRDF to do it such that RDF statements might be able to be extracted from the document.

Or I'm working through news articles doing a content tagging.