Aryeh Gregor wrote:
On Tue, Jul 7, 2009 at 4:46 PM, Brion Vibberbrion@wikimedia.org wrote:
Technically HTML 4 is pretty much the same in this regard; it's 100% legitimate SGML and HTML 4 to skip implied opening and closing elements, drop quotes on attribute values that are unambiguous, etc.
Not entirely. HTML 4 doesn't allow you to omit quotes on attribute values that contain non-name characters, for instance, at least according to the W3C validator -- so you need quotes for all URLs, for example. These aren't necessary either in practice, or in HTML 5. I'm pretty sure the requirements for opening and closing elements are stricter in HTML 4 as well.
Remember Postel's robustness principle (paraphrased):
be conservative in what you send, liberal in what you accept
If quotes are always permitted, then always send the quotes.
If closing tags are always permitted, then always send the tags.
The browsers will handle them, and we don't need to worry about the flavor of browser.
There's no need to over-optimize the output. The intended viewer isn't human, and we're not talking about enough extra characters that very slow links will be congested....
HTML 5 tends to loosen things up to whatever all browsers support, which is usually more lenient than what HTML 4 formally allows. It also actually specifies what constructs must be supported, in painstaking detail, so you can figure out what's legal without dumping it in a validator and hoping the validator's correct . . .
Great. Does that mean HTML 5 browsers will still accept formal HTML 4?
Then, let's stick to the "stricter" interpretation.
On Tue, Jul 7, 2009 at 4:49 PM, Brion Vibberbrion@wikimedia.org wrote:
XML formulation could perhaps be useful if we migrate page text storage from custom markup to an HTML-based internal format, as we could then toss it at XML parsers without worrying. But that doesn't have any bearing on the HTML user interface we display to end-users in browsers.
Does that mean "go ahead and begin switching to HTML 5 now", or what?
My thought is that the 5 tags that are marked as well-supported could be used, but be very cautious about abandoning 4. There are a lot of old machines out there, and many cannot upgrade to newer browsers, because they cannot upgrade their underlying operating systems.
For example: schools, already heavy *pedia users. And political campaigns often use cast-off machines. Win98 or 2K means no upgrades.