[whatwg] HTML5: compatible with all legacy Web browsers

Thu Aug 13 20:16:07 PDT 2009

On Thu, 6 Aug 2009, Elliotte Rusty Harold wrote:
>
> Section 1.7:
> 
> "The first such concrete syntax is "HTML5". This is the format 
> recommended for most authors. It is compatible with all legacy Web 
> browsers."
> 
> I challenge the claim that HTML5 is compatible with *all* legacy Web 
> browsers. I can produce valid HTML 4 documents today that are not 
> compatible with *all* legacy Web browsers. I suggest this be weakened to 
> something like "is compatible with most Web browsers still in active use 
> today".

Changed "all" to "most".

On Fri, 7 Aug 2009, Simon Pieters wrote:
> 
> I guess the following is an example of a valid HTML5 document that is 
> incompatible with legacy Web browsers:
> 
>    <!doctype html>
>    <title></title>
>    <svg><script/></svg>
>    <p>Hello world</p>

It's certainly possible to use the language in a way that is incompatible 
with legacy UAs. 

On Fri, 7 Aug 2009, Aryeh Gregor wrote:
>
> I think the meaning of "compatible with all existing browsers" here is
> that HTML 5 does not *require* authors to break compatibility with any
> existing browser.

Exactly.

> Clearer wording might be like, "HTML5 pages can be written to be 
> compatible with all legacy Web browsers."  Of course, "all legacy Web 
> browsers" does need to be construed to exclude Netscape Navigator 3 and 
> such.  If you really want to be picky, it could be "all legacy Web 
> browsers that still see significant use."

I think just saying the language is compatible is probably clear enough.

On Fri, 7 Aug 2009, Erik Vorhes wrote:
> 
> I agree completely with your interpretation of the phrase. HTML5 is 
> intended to enhance the web without breaking it, so noting (or even 
> emphasizing) how it's backwards-compatible is important and useful.
> 
> But the phrase should be clarified along similar lines to what you've 
> articulated. Maybe: "HTML5 can be written in such a way that it is 
> compatible with all browsers made after X date"?

I don't think most people reading this are really going to be confused 
either way on this.

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