[OrcaDK]

Making an XML schema would be anything but a waste of time. Admitted, you won't get any sites to use it though.

I myself used an internal XML schema when i made a HH parser some time ago. I several plugins that simply read the sites HH and converted it to the uniformly XML format that i had specified. In that way my HH parser would only have to think about one format, and users could easily write plugins to support new formats.