How can semantics be added?
There are at least three approaches to adding semantics. (a) Creating a generally agreed tagset. HTML is the best example of this and all HTML-compliant software treats in the same way, i.e. a hyperlink. Other tagsets (formally referred to as Document Type Definitions or DTDs) may treat in other ways (author, answer, etc.). XML itself does not create tagsets, but some of its applications (such as XSL, the eXtensible Stylesheet Language, and SVG, Structured Vector Graphics) do. It is likely that the W3C will sanction in the region of 10-20 DTDs for use in horizontal application, including Mathematics, but this will not extend to chemistry. In this article we propose a base set of tags for markup in chemistry. Meaning can be added to a fixed tagset either by reformatting the input so that humans instinctively understand it (e.g. bullets can be added before 
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