Amanda sent me a YouTube link on the theme of Web 2.0 a few weeks ago. I was reading about James Watt (1736-1819) at the time, for a feature.

Watt devised a radical improvement for the widely-used but inefficient Newcomen steam engine, by simply separating out a key process into an external mechanism.

It struck me that this was a lot like XHTML, and a fundamental principle of XML …