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Re: HTML5 alt conformance criteria clarifications requested

From: James Graham <jg307@cam.ac.uk>
Date: Sat, 16 Aug 2008 18:33:51 +0100
Message-ID: <48A70F7F.1060006@cam.ac.uk>
To: Steven Faulkner <faulkner.steve@gmail.com>
CC: Ian Hickson <ian@hixie.ch>, W3C WAI-XTECH <wai-xtech@w3.org>, "public-html@w3.org WG" <public-html@w3.org>

Steven Faulkner wrote:
> hi jgraham,
> yes, my bad you are correct on the title/description.
>
>   
>> I believe the spec currently requires that flickr set @alt={photo} or
>> similar.
>>     
>
> so does this mean it is what is required in these cases or you are not
> clear on what is required?
>   
Well I guess I was wrong in a sense because it depends entirely on what 
context the photo appears in. I was only considering the individual 
photo page case but actually there are a fairly large number of distinct 
cases.

On the user's home page (e.g. [1]) the photos are the sole contents of a 
link so per section 4.7.2.1.1. the alt text must "convey the purpose of 
that link". This suggests that the alt text in this case could be "Photo 
page" or similar. I guess adding the title of the photo e.g. "Photo page 
for Mario's Bike" would help in the case where someone wanted to query 
the images out of context but would be repetition in the case where the 
page was being read linearly. However I'm not sure that the spec has 
anything to say on the topic.

On the individual photo page (e.g. [2]) the photo is not a link and the 
image is clearly a key part of the surrounding content. Therefore 
Section 4.7.2.1.8. applies. At this point the alt text should contain a 
textual equivalent of the image unless no such alternate text is 
available. Clearly (from observing flickr) none of the fields provided 
are reliably used to provide textual equivalents of images. Therefore we 
are always in the case where there is no textual equivalent avaliable so 
we must supply an alt that provides a categorization of the image 
delimited by curly braces e.g. alt={photo} (there is no requirement that 
the exact string {photo} be used but it must be a classification of the 
image).

On some aggregate photo pages such as a group pool or a user's set (e.g. 
[3], [4]) the images are again the sole contents of links and so 
4.7.2.1.1. again applies. In this case however, there is no context to 
give e.g. the name of the photo so using  something like alt="Photo Page 
for New Forest Pony". Arguably the text "Photo Page" is unnecessary 
although this does create a (relatively common) edge case when the photo 
has no title (note also the requirement to be careful here to avoid 
using titles that are delimited by curly braces directly in @alt).

On some search pages, explore pages calendar pages and explore front 
page (e.g. [5], [6], [7]) the photo is again the sole contents of a link 
but the other information about the photo is already supplied. This case 
is quite close to the user's stream page case.

Did I miss any cases?

[1] http://flickr.com/photos/jgraham
[2] http://www.flickr.com/photos/andrerabelo/70458366
[3] http://flickr.com/groups/utata/pool/
[4] http://flickr.com/photos/rebba/sets/72157594157565155/
[5] http://flickr.com/search/?q=sigur+ros&s=int
[6] http://flickr.com/explore/interesting/2008/08/15/
[7] http://flickr.com/explore/
Received on Saturday, 16 August 2008 17:34:29 GMT

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