[whatwg] Using the HTML5 DOCTYPE as a new quirksmode switch

Mihai Sucan mihai.sucan at gmail.com
Tue Mar 13 10:03:41 PDT 2007

Le Tue, 13 Mar 2007 18:04:39 +0200, Colin Lieberman <colin at fontshop.com> a  

> I'm not sure how this is a backwards compatibility issue. My  
> understanding is that user agents aren't actually parsing information  
> from the doctype, just checking for its existence. The only applications  
> that should break are validators, which would need to be updated anyway.
> I ran some quick (and highly unscientific tests) on ff1.5 and ie7 (both  
> pc) with a real html 4 doctype, <!DOCTYPE html>, and <!DOCTYPE html5>  
> (both with and without a space before the 5), and nothing broke in terms  
> of rendering or function.
> Please let me know if there's something I'm missing here.
> Thanks,
> Colin Lieberman

You can't simply invent any DOCTYPE definition, while having it backwards  

Here's a tutorial about DTD, which also explains the DOCTYPE line:

<!DOCTYPE root-element [element-declarations]>

The root element in HTML5 is "html", not "html5".

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