Re: "downplayed errors"

On Tue, Feb 10, 2009 at 11:37 AM, Robert J Burns <rob@robburns.com> wrote:

>
> On Feb 9, 2009, at 8:32 PM, Ian Hickson wrote:
>
>>
>> As far as I can tell we already have consensus on alt="" being required.
>> (With one or two exceptions, the spec requires alt="" to be present. The
>> exceptions are machine-checkable.)
>>
>
> I can't imagine at all how you think these could be machine-checkable
> criteria when it comes to omitting alt. Could you tell us a little about
> what you're thinking?
>

There are three bullet points in 4.8.2.1.9 that are machine-checkable when
@alt is omitted.  The <figure> and <article><h1> cases are pretty
semantically specific.  The @title case is a little less specific. (There
may be more cases where @title may be present but don't match the semantics
for when @alt is omitted - key part of content with no suitable alternate)

Does that make sense?

To me the easiest way to make this machine checkable is to remove those few
> conditions that allow the alt attribute to be omitted and always require the
> attribute (of course allowing authoring tools to produce non-conforming
> documents when authors fail to provide conforming alt text as any other case
> when an author uses an authoring tool to produce a non-conforming document).


And then in doing so you make the semantics of those more ambiguous and less
machine-checkable (irrelevant vs. relevant images) - unless we go back to
the discussion of adding extra markup for those cases (another thread, I'm
sure).

As it stands, machines can give better error and warning messages for <img>
elements covering more varied use cases.

-- 
Jon Barnett