Re: Rethinking HTML 5 (Was: Re: Semicolon after entities)

Gareth Hay wrote:
>> You are incorrect. The WHATWG specs as defined are (loosely speaking) a
>> superset of HTML 4 (in that they add useful features) and are also
>> backwards compatible.
> 
> Hang on, you can't say "HTML5 will display  "correctly" in browsers that
> are HTML5-unaware" and then say "The WHATWG specs as defined are
> (loosely speaking) a superset of HTML 4 (in that they add useful features)"
> 
> Well, you clearly did, but how can you have something which is a
> superset (more features) rendering correctly in something that knows
> nothing about those new features.
> 
> It makes no sense at all.

Ok. Let's use an example: the new video element. Whether you like it or
not is irrelevant. This is about backwards compatibility.

<video src='my.mov'></video>

Obviously, that's not going to display my.mov in existing browsers
(unless they're farther along than I expected, but let's just use IE. It
certainly won't). BUT, the nice thing is, whatever's inside is fallback
content. So,

<video src='my.mov'>Upgrade your browser, fool.</video>

Acts as you would expect. In an HTML5 compliant browser, the video
plays. In an old browser, you get the message (which is hopefully more
polite). Alternatively, you can do something like this:

<video src='my.mov'><object data='...'>...</object></video>

(but fill in the appropriate details for the object). Or if you want you
can script it to turn older browsers with javascript into HTML5
browsers. (doing this is an exercise left to the reader).

This is what we mean by backwards compatibility.