[html4all] Object element support

[Jason White]

On Sat, Aug 23, 2008 at 12:21:54PM +0300, Robert J Burns wrote:
> That important difference is that one mechanism is for alt text — text  
> that is to be replaced and serve as a seamless replacement for the  
> embedded media — and the other mechanism is for descriptive text  
> equivalents — text that is a subject or visual description of the  
> embedded media not necessarily suitable to replacing the media in the  
> present document.

An alternative approach, which I favour, is to collapse this distinction by
holding that there is only one alternative needed, namely, whatever can serve
as a seamless substitute for the embedded media. Either this substitute is
adequate to fulfill the purpose or convey the information served by the media
in the context of the content, or it is not.

In the first case, any additional description would be superfluous. In the
second case, the alternative needs to be more explanatory or descriptive, as
appropriate, so as more adequately to serve as a substitute for the embedded
media.

This is the premise on the basis of which WCAG 1.0 and 2.0 requirements are
defined.

I also disagree with the claim, introduced earlier in this thread, that there
are two categories of users, one of which would supposedly be served by the
seamless substitute, and the other of which would need, or benefit from, the
additional description. To the contrary, there is one category of users,
namely those whose delivery context precludes viewing or listening to the
embedded media, whether temporarily, as may be due to environmental or
technological circumstances, or permanently, in the case of the user's having
a disability. However, the circumstances giving rise to the need don't alter
the nature of that need, namely for a seamless and adequate substitute.

While I appreciate the thinking that underlies Rob's distinction, I don't find
it compelling and I don't think it should serve to influence markup language
design. Moreover, WCAG does not draw such a distinction, and I would argue
that it should not.

With apologies for entering the discussion purely to make a negative point, I
nonetheless hope this contrary view helps more than it hinders.

To explain a little further, I think it is a matter of style on the part of
the author whether to provide a seamless substitute "in place", or whether to
provide part of that substitute - a label or a brief explanation - in place,
and then to include a link to additional details that give the missing
explanatory or descriptive material.

I earlier argued that if the substitute is adequate, then additional
description is superfluous. It may be useful to provide such a description,
but it is not an accessibility requirement to do so - if it were, then the
supposed substitute would be inadequate as a genuine alternative to the media.