This post is from one of several previous incarnations of this site and probably doesn’t quite fit the current format. In a former life this was a group blog and a tumblelog before it became a static jekyll site. If anything looks broken or is worded oddly that could be why. Pardon the dust.
A nice clear guide to unravelling the syntax of the W3C’s (X)HTML definitions. Helpful for getting to the bottom of what’s allowed where.