[whatwg] HTML syntax: shortcuts for 'id' and 'class' attributes

Andrew Fedoniouk news at terrainformatica.com
Thu Nov 30 21:18:41 PST 2006

----- Original Message ----- 
From: "Boris Zbarsky" <bzbarsky at mit.edu>
To: "Andrew Fedoniouk" <news at terrainformatica.com>
Sent: Thursday, November 30, 2006 9:03 PM
Subject: Re: [whatwg] HTML syntax: shortcuts for 'id' and 'class' attributes

> [off list, since it's totally the wrong list]

Oops, didn't realize that, terribly sorry.

> Andrew Fedoniouk wrote:
>> 1) HTML5 is backward compatible with HTML4 so any HTML5 aware UA can read 
>> HTML4 files
>> without any additional setup. That implies HTML4 is a subset of HTML5.
> HTML4 is not a subset of HTML5.  But HTML4 that's actually used on the web 
> is a subset of HTML5, generally speaking.  Thus any HTML5 aware UA can 
> render the HTML4 that's used on the web.
>> 2) Any HTML4 aware UA can render HTML5.  That is possible only if HTML5 
>> is exactly HTML4 or its subset (but not superset).
> HTML5 is not a subset of HTML4.  But it's designed in such a way that it 
> takes advantage of the extensibility features of HTML4.  Thus an HTML4 UA 
> can render an HTML5 page reasonably, though possibly not as well as an 
> The change you suggest would mean that HTML5 and HTML4 UAs would need 
> totally different behavior, which is not desirable.
> -Boris

So if  HTML5 will allow following:

<p.myclass> ... </p>
together with its full and equivalent form
<p class="myclass"> ... </p>

then this will be backward compatible solution as
HTML5UA will understand both forms - classic and simplified.
Am I right?


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