Aryeh Gregor wrote:
On Tue, Jul 7, 2009 at 4:46 PM, Brion
Vibber<brion(a)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
Vibber<brion(a)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.