W3C home > Mailing lists > Public > public-html@w3.org > August 2007

Re: transparent content model and proposed ALT element

From: Jason White <jason@jasonjgw.net>
Date: Sat, 4 Aug 2007 16:33:09 +1000
To: public-html@w3.org
Message-ID: <20070804063309.GA7908@jdc.local>

On Sat, Aug 04, 2007 at 01:00:36AM -0500, Robert Burns wrote:

> Thanks for that explanation. That's the best explanation I've see for what 
> a transparent content model is (or in this case a transparent element 
> type). I assume this means that, in a strictly inline -level context, the 
> ALT element must have a strictly inline-level content (with structure 
> inline context, it could be otherwise?). 

This is, as I read the draft, correct.
> However, I was thinking of an ALT element as more of a hidden element in 
> visual media browsers. Something that would be there in the document tree, 
> waiting to be swapped in for the primary content. In that sense the content 
> model surrounding the ALT element would be irrelevant (however I think in 
> this case it would be best for this element to just occur where block-level 
> elements are expected).

I suppose this is partly a matter of taste, but it seems better to allow
authors to place the ALT element within the same block-level parent as an
inline IMG, EMBED, VIDEO or AUDIO, if they so wish. This is why I suggested
allowing ALT in both block-level and inline contexts.

As I read the draft, this is what is meant by "structured inline".

The transparent content model, with the meaning clarified above, is important
as it allows the alternative content to consist of an inline link or
explanation, or an entire block-level structure.
> More and more, though I think its the FALLBACK element that should be the 
> one we're concerned about. This should be the element that is hidden or 
> whose display is none (in CSS) in screen/print (visual) media. We could 
> also have an attribute on FALLBACK to let authors designate whether they 
> should be hidden or not. By not hiding the FALLLBACK element it would 
> provide a way to display alternates along-side primary content (if that's 
> what the author was after) . Then the ALT element would always occur in a 
> FALLBACK element. The FALLBACK element would simply provide a container for 
> marking up alternate equivalents.

Allowing multiple ALT elements, with @for values that refer to the same media
element, would achieve the same purpose as your FALLBACK element proposal. It
would be straightforward to add a boolean attribute serving as a hint to the
user agent that, if the media element to which @for refers is rendered, the
content of ALT should be hidden. Debate, I am sure, would then ensue regarding
the default value of this boolean attribute.

To summarize: I don't think HTML needs a FALLBACK element, but I still favour
the addition of an ALT element, or a comparable mechanism achieving the same
Received on Saturday, 4 August 2007 06:33:16 UTC

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