W3C home > Mailing lists > Public > www-math@w3.org > September 2010

Re: self-closing tags in html5

From: William F Hammond <hammond@csc.albany.edu>
Date: Mon, 20 Sep 2010 13:56:47 -0400
To: Henri Sivonen <hsivonen@iki.fi>
Cc: public-html@w3.org, Ian Hixie <ian@hixie.ch>, www-math@w3.org
Message-ID: <i7k4mgxpr4.fsf@hilbert.math.albany.edu>
I'm not subscribed to "public-html".  I had hoped that the list
manager would allow my previous message to go through, but that has
not happened.  So if you include that list in your reply, please quote
in full what you're replying to.

Henri Sivonen <hsivonen@iki.fi> writes to public-html@w3.org:

> For which values of X and Y? I see the exact same serialization in
> the latest Firefox trunk nightly (Mac) and in IE8 (Windows XP).

Firefox 4 and IE-8 are both correct on this.  X and Y are others that
I did not want to name in public.  My point was that the incorrect doms
built by X and Y trip up MathJax in different ways.

>> I think that things might work better if all self-closing tags,
>> foreign or not, i.e., marked up in the form "<foo/>", are recognized
>> as empty elements, whether defined-empty or merely de facto empty.  Of
>> course, if "foo" is the name of an element in the short list of
>> defined-empty html elements, it should still be the case that "<foo>"
>> is recognized as indicating an empty element.  It would certainly be
>> simpler for building the dom skeleton this way.
>
> For backwards compatibility reasons, it's not OK to make <foo/> act
> as self-closing syntax when foo is an HTML element. On the other
> hand, where foo is a MathML element, we don't need to make <foo>
> (without the slash) self-close, since introducing that level of DWIM
> isn't necessary for compatibility.

This statement about backwards compatibility is often asserted, but I
doubt its truth.

Consider the small html4.01-strict document
http://math.albany.edu/pers/hammond/Test/tb7.html

It contains the following nonsense (that Firefox, Google Chrome,
IE-8, lynx, Opera, and w3m correctly IMO do not render):

         <p/Tiny paragraph.>

Because the sgml declaration for html4 unwisely allowed full use of
SHORTTAG, this document validates with opensp.  However, the W3C
validator puts out a warning message: "NET-enabling start-tag requires
SHORTTAG YES".

But the error -- not a warning -- (and the rule) should be:

   NESTC tag '/' not immediately followed by null end-tag '>'

And, as I said, this one rule should work well in the text/html
serialization of html5 in both foreign and domestic namespaces.

BTW it's easy enough to fix the SHORTTAG issues in the sgml
declaration for HTML 4.  See
http://math.albany.edu/pers/hammond/ht4decl-diffs

                                    -- Bill
Received on Monday, 20 September 2010 17:57:26 GMT

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