- From: Ian Jacobs <ij@w3.org>
- Date: Tue, 09 May 2000 16:22:02 -0400
- To: w3c-wai-ua@w3.org
Hello, At the 9 May teleconference, we discussed minimal requirements for checkpoint 2.5 of the 7 May draft [2]: <OLD> Checkpoint 2.5: When the author has not specified a text equivalent for content as required by the markup language, make available other author-specified information about the content (e.g., object type, file name, etc.). </OLD> This email consists of two parts: proposed clarification of text and minimal requirements summary. 1) New text. It is not clear (enough) from checkpoint 2.5 that the user agent is expected to repair the case where the author has not provided any text equivalent. This checkpoint is only meant to apply for those objects where the user agent can recognize content as being a text equivalent of some other piece of content (that's in the applicability provisions of the 7 May draft). The checkpoint doesn't say "a text equivalent for non-text content". I think we should say that. Also, the checkpoint talks about a text equivalent "as required by the markup language". I think that is meant to capture "that the user agent can recognize", but I don't think that's sufficient for two reasons: - Even if the markup language doesn't require it, the user still needs it. - The author may provide text equivalents in the objects themselves, and not in the markup (though you can argue that this markup for the object). For instance, consider the W3C Note entitled "Describing and retrieving photos using RDF and HTTP". Some image formats (e.g., JPEG) let you store metadata in them, and the user agent should make use of this information when available. Therefore, I propose the following clarification: <NEW> When the user agent cannot recognize a text equivalent for non-text content, generate a text equivalent from other author-supplied content. </NEW> This wording does place a slightly heavier burden on the user agent. In the previous wording, the user agent wasn't required to do anything if the author provides a text equivalent but the user agent doesn't recognize it. In the proposed wording, as soon as the UA doesn't recognize a text equivalent, the repair function applies. Notes: - We should state in the techniques that text equivalents may come from markup, inside images, etc. User agents are expected to recognize equivalents by specification (a reminder of what the applicability clause already states). - The user agent, by virtue of generating the text equivalent itself, knows about the association between the generated equivalent and the object. Therefore, other checkpoints (e.g., 2.3) that involve recognized equivalents would apply for these generated equivalents. I also propose that we add the RDF/photos note to the list of references in the Techniques document. 2) Minimal requirements. We agreed at the teleconference that the requirement was to make available both the resource name and type. This information is available from HTTP headers. 1) Name. This is some or all of the URI of the requested resource. In the case of content negotiation, the "Content-Location" header may provide information. 2) Type. This information is available in the Content-Type header. - Ian [1] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000AprJun/0327.html [2] http://www.w3.org/WAI/UA/WD-UAAG10-20000507/ [3] http://www.w3.org/TR/2000/NOTE-photo-rdf-20000503 -- Ian Jacobs (jacobs@w3.org) http://www.w3.org/People/Jacobs Tel: +1 831 457-2842 Cell: +1 917 450-8783
Received on Tuesday, 9 May 2000 16:23:11 UTC