- From: Sander Tekelenburg <st@isoc.nl>
- Date: Sun, 5 Aug 2007 02:21:59 +0200
- To: public-html@w3.org
[I see you already pointed to a couple of things I just posted about. Sorry about that. I normally read an entire thread before posting to it. My mistake for not doing that this time.] At 22:06 -0500 UTC, on 2007-08-03, Robert Burns wrote: [... @type for MIME types, so doesn't allow more generic indication] > The @type attribute is not always a MIME type. The INPUT and BUTTON > elements both have types that are not MIME types, but simple > classifications just like this proposal. That's true, I didn't think of that. However, I must say that as an author I find such context-sensitive meanings of attrtibutes confusing. So my initial take would be to dismiss using @type for non-MIME types here. Also, I believe there is a need to provide both advisory MIME types *as well as* advisory information about the 'sort' of equivalent. For example, a captioned video might in itself be useful to a user, but when it is in a file type format that his system can't consume, it is useless. So allowing <alt for=idref title="captioned video" type="video/ogg"><video></a>, would probably be useful. Both attributes would provide complimentary advisary information. Authors could then do: <video id="speech"></video><!-- folowed by any or no content --> <alt for="speech" title="captioned video" type="video/ogg"><video></video></a> <alt for="speech" title="captioned video" type="video/mpeg"><video></video></a> <alt for="speech" title="audio only" type="audio/ogg"><audio></audio></a> <alt for="speech" title="audio only" type="audio/mpeg"><audio></audio></a> <alt for="speech" title="transcript" type="text/html">marked up textual equivalent</a> <alt for="speech" title="transcript" type="text/plain">plain text equivalent</a> Only issue is, what if the UA supports both MPEG and OGG? Answering myself, I suppose a UA could be configured to favour one over the other, presenting only the favoured file format. Or a UA could present bth options as - captioned video [OGG] - captioned video [MPEG] and leave the rest of the work up to the user. Might well be good enough formost users. [...] > As for distinguishing between different > equivalent types, I think a @type attribute would be good (we could > also have @contenttype to provide two different ways to classify the > element). FWIW, I think that would add too much to author confusion of when type takes what sort of information. I would be OK with using @type for non-MIME types if for all cases where it takes MIME types we would replace it with @contenttype. But such a big change would probably generate new problems. Using @title and @type would appear to be less dramatic. [...] > I had earlier suggested a LONGDESC element (ALT, EQUIV, FALLBACK or > LONGDESC all work for me). At least for a one-to-one relation, to me > it makes more sense to use the @lkongdesc attribute from the original > element. To go from primary ---URL---> fallback rather than > referencing from fallback ---IDREF---> primary. For a mere "one equivalent only" solution that might indeed work, yes. I don't understand how it would work for multiple equivalents thogh: > Multiple equivalents > could be handled by letting ALT have a content model that includes an > initial ALT or adding a @longdesc attribute to ALT too. Sorry, I can't follow. (Perhaps some example mark-up would help me understand what you mean.) [...] > However, I think the for=IDREF approach works better for specifying a > one-to-many relation between primary and equivalents (without any > implicit or intended ranking). Ah, OK:) > Another advantage for both approaches (specifying an ALT element > whether Jason's way or the way I'm suggesting) is that either works > easily in a backwards compatible way with an HTML5 specific style > sheet (with style declarations like something like "ALT {visibility: > hidden;}" or "@screen {ALT {display: none}}" With very minimal java > scripting, we could probably even emulate the role we want UAs to > play to provide a mechanism for users to switch between equivalents > in non-HTML5 conforming UAs. Indeed. -- Sander Tekelenburg The Web Repair Initiative: <http://webrepair.org/>
Received on Sunday, 5 August 2007 00:30:31 UTC