Are numbers not allowed in html5? In XML the [starting character](http://www.w3.org/TR/xml/#NT-NameStartChar) is different. This would apply to xhtml as well. In html5 I don't see that [attribute name](http://www.w3.org/TR/2011/WD-html5-20110525/syntax.html#syntax-attribute-name) limitation.

It appears the DOM (provided by libxml) might have a limitation over html5.

I did some testing in chrome and firefox, to see some other implementation. They don't allow numbers as the first character in practice.

All of this is to say I did some legwork around numbers and I wanted to document it for the day we come back to this same issue. I'm ok with this for now. Though, I reserve the right to root @technosophos on as he writes a custom DOM some day in the far far future.