Disclaimer: Not a WG response.
On Mar 5, 2008, at 16:33, Bert Bos wrote:
On Wednesday 05 March 2008 05:28, Ian Hickson wrote:
On Wed, 5 Mar 2008, Bert Bos wrote:
The HTML5 WD states (section 1.1.1[1]) that the format is meant to
be as much backwards-compatible as possible. With a little change
to section 8.1.1[2], HTML5 could, in fact, be fully backwards
compatible.
What do you mean by backwards compatible in this context? HTML5
doesn't claim that all legacy documents are conforming HTML5
documents (in fact no legacy documents are conforming HTML5
documents);
Yes, and I wonder why. HTML5 can easily say that (most? all?) valid
HTML4 document are also valid HTML5 documents.
[...]
Yes, it is. Once HTML5 is a REC, *it* defines HTML (see, e.g.,
sections
1.3 and 1.4.1) and HTML 4.01 is no longer relevant. It would be a pity
if old documents suddenly stopped being HTML, when they only differ in
a line that is "mostly useless" (as the draft says).
First, I agree that there's no *technical* reason why HTML 4.01 could
not be rescinded and *some* HTML 4.01-looking doctypes be made
conforming as HTML5.
It's nice that HTML5 takes forward compatibility into account (by not
including a version number in document instances), but I don't see why
it has to break with the past. I know previous versions of HTML had
the
same problem, but that is not a reason to repeat the mistake.
I've argued previously that in order for the current HTML5 to HTML6
forward-compatibility story to be believable, the same story should
apply to the HTML4 to HTML5 transition:
http://lists.whatwg.org/pipermail/help-whatwg.org/2008-February/000126.html
Here are some complicating points in no particular order:
* Making doctypes that say "HTML 4.01" conforming as HTML5 will
confuse some people who have not yet internalized the notion that Web
formats shouldn't have versions with which the language grows and
shrinks but only levels that grow the language monotonically.
* We shouldn't make quirks mode doctypes conforming, which means
that some doctypes that were conforming under HTML 4.01 have to be non-
conforming.
* We probably shouldn't make the almost standard mode doctypes
conforming, either, as long as the distinction between almost
standards and standards modes is maintained in Gecko/Opera/WebKit.
However, the almost standards mode is the common case among pragmatic
standards-aware developers today. Therefore, it seems to me that in
order to reap a notable practical benefit from making some legacy
doctypes conforming, the CSS WG would need to fix the CSS defaults to
match the almost standards mode so that the need for distinguishing
the almost standards mode and the standards mode would go away.
http://lists.w3.org/Archives/Public/www-style/2008Jan/0598.html
* Valid HTML 4.01 formally includes various weird SGML stuff
(minimizations in particular) that have never been supported by
mainstream browsers. We shouldn't make that stuff conforming. Hence,
we can't categorically make valid HTML 4.01 documents valid HTML5
documents.
* HTML 4.01 has some above-SGML-layer bits that are so bad and
rarely used that we should take the opportunity to ban them: The way
isindex is implemented in browsers is fundamentally incompatible with
the generally understood relationship of markup and the DOM. basefont
is obsolete in practice. This is another reason why we shouldn't
categorically make valid HTML 4.01 documents valid HTML5 documents.
* On a number of other points mainly pertaining to presentational or
redundant attributes (in particular border=0, target=_blank,
language=JavaScript and presentational attributes on tables that were
allowed in 4.01 Strict) I think we indeed should make more HTML 4.01
usage patterns conforming even if the patterns are no-ops or would
have more elegant CSS alternatives.
http://lists.w3.org/Archives/Public/public-html/2008Jan/0305.html
http://hsivonen.iki.fi/test/moz/happycog-portfolio-results.txt
--
Henri Sivonen
[EMAIL PROTECTED]
http://hsivonen.iki.fi/
