W3C home > Mailing lists > Public > www-tag@w3.org > October 2003

RE: Action item on the virtues of error-handling

From: David Orchard <dorchard@bea.com>
Date: Wed, 22 Oct 2003 09:56:43 -0700
To: "'Dan Connolly'" <connolly@w3.org>
Cc: "'Masayasu Ishikawa'" <mimasa@w3.org>, <www-tag@w3.org>
Message-ID: <00cb01c398bd$79339390$6701a8c0@beasys.com>


> >  To facilitate experimentation and interoperability between
> >    implementations of various versions of HTML, the
> installed base of
> >    HTML user agents supports a superset of the HTML 2.0 language by
> >    reducing it to HTML 2.0: markup in the form of a
> start-tag or end-
> >    tag, whose generic identifier is not declared is mapped
> to nothing
> >    during tokenization. Undeclared attributes are treated
> similarly. The
> >    entire attribute specification of an unknown attribute (i.e., the
> >    unknown attribute and its value, if any) should be ignored.
> >
> > I assert that this is the "must ignore" rule for elements
> and "should
> > ignore" for attributes.
>
> I don't see "must" in there anywhere.
>

It seems clear to me the intent.  Perhaps the spec could have been written a
bit better:
"whose generic identifier is not declared is mapped" -> "whose generic
identifier is not declared must be mapped".

I believe that "is" statements are the equivalent of must.

I guess that a true html 2.0 conformant browser could NOT map undeclared
identifiers to nothing, such as throwing an error.  But I betcha almost all
treat the "is" as "must".

>
> > During the time of the most innovation was happening in
> HTML, from 2. to 4.,
> > the must ignore rule was in effect.
>
> It went back to 1.x, during the introduction of <img> and such.
> But any implementation that ignored <form> did so at peril of becoming
> totally irrelevant.

There is that.

>
> There's a valuabel pattern of ignoring stuff in there, but it does no
> good to call it "must ignore", and to endorse it without
> reservation is a disservice to our readership. Noting the downside
> is important.
>

So let's quibble a bit more on whether it is "must" ignore" and also write
down the downsides.  I don't yet see any text from you on what the downsides
are.

I'm not really sure where you are going with this line of objection and more
importantly what text you'd like instead.  I think the text is darned good
and am happy to include it in the arch doc.

Cheers,
Dave
Received on Wednesday, 22 October 2003 12:56:44 GMT

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