If you care about the intricacies of the difference between programming languages and markup languages for document and data reprepresentation, see the ironically named "The Origin of (Document) Species", by Khare et al. at http://www.cs.caltech.edu/~adam/papers/www/origin-of-species.html Despite being one of the perpetrators, I'd observe we are wondering of the TDWG charter a little here....