“It is not, and has never been, valid HTML to write `<br></br>`.”
Sure, but note that it is perfectly valid XHTML (which is a form of HTML).
Oh, and `<script src="foo" />` actually works the way you’d expect it to in XHTML.
Don’t use XHTML though.
Unless you want to combine it with SVG for a hybrid site [1].
[1] view source on http://emacsformacosx.com
You are saying that XML hybrid document stuff doesn't work in "real" browsers? Do IE, Firefox, Safari, Chrome and Opera not count as "real"?
Just to be clear, I'm saying the hybrid XHTML/SVG works just fine in all major browsers.
That's right, I just Godwin'd you.
It seems better to mix that with SVG than HTML5, since SVG happens to also be XML based. Otherwise you have a impedance mismatch leading to some weird corner cases.