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Re: unifying alternate content across embedded content element types

From: Robert Burns <rob@robburns.com>
Date: Sat, 14 Jul 2007 23:30:49 -0500
Message-Id: <D82A619B-98CC-4CEA-B569-84E55ABAF7D7@robburns.com>
To: HTML Working Group <public-html@w3.org>


On Jul 14, 2007, at 10:28 PM, Jon Barnett wrote:
>>>  [...] context is often equal to fallback. There are cases where  
>>> the context
>>> and
>>> the fallback would be exactly the same
>>
>> Could you give an example? I'm having a hard time thinking of one...
>
> <img src=cat.jpg alt="A photo of my cat, Fluffy, playing with a  
> ball of yarn">
> <p>A photo of my cat, Fluffy, playing with a ball of yarn</p>
>
> figure/legend helps with this by directly associating the photo with
> the description Expecting me to provide that @alt attribute along with
> the following paragraph seems silly and redundant.  If that's not what
> I should provide for @alt, then it should be crystal clear what I
> should provide as @alt

I would agree. If you provide textual description of an image near an  
image, then it should not be repeated in the @alt attribute. However,  
there has to be a way to let a vision impaired user or someon who  
cannot load the picture what they're missing. For example, in this  
case simply alt="Fluffy" might be enough. Again this all depends on  
your audience. If your audience already knows who Fluffy is,, then  
you don't need to say "My cat Fluffy ...", you could just start  
"Fluffy..." I bring this up because much of the discussion going on  
seems to neglect that much of this depends on an author and the  
author's targeted audiences. If this is a page for your family and  
close friends. They already know your cats name.

>>>  I think better defining the markup for a semantic "equivalent"  
>>> vs. a
>>> semantic "alternate" is more useful than defining markup for  
>>> "long" vs.
>>> "short".
>>
>> Sorry, you've lost me. I don't know what "long vs short" refers  
>> to, and don't
>> understand what "semantic equivalent vs semantic alternate" means.
>
> Most of this thread has been about various ways of providing "short"
> alternative in addition to a "long" alternative, such as using @alt
> and @longdesc together, and using a hypothetical <object alt='...'>
> attribute in addition to the contents of alt.  I thing this confuses
> the issue of alternative content more than it goes to solve it.  I
> think the more relevant issue is "descriptions" of media vs.
> "equivalents" to media.

That's fine if you don't want to refer to it as long and short,  
However, I'm having trouble understanding what the terms you're using  
of "semantic alternate" and "semantic equivalent" Couldn't you just  
substitute the terms as you understand them for the terms others are  
using and respond. In other words adding the @alt attribute to  
<object> would mean adding an attribute for semantic alternate  
content while the contents of the <object> element would be for  
semantic equivalent (am I using your terms correctly?). Likewise, the  
<img> element already offers and @alt attribute for semantic  
alternate and a @longdesc attribute to target semantic equivalent.

> Were the examples I gave not clear enough as to what I meant?

No, I think it helps to provide concrete examples like with Fluffy:  
especially if you want to introduce new terms for this content.

>>>  Are the contents of <object> an equivalent or a description?   
>>> Both, in
>>> certain cases?
>>
>> In HTML 4.01 the content of <object> is the equivalent content:
>
> I suspect that most commonly in the wild, the contents of <object> are
> actually a description of the media instead of an actual equivalent to
> the media.  It would be interesting to gather data on this.  Is there
> a convenient way for me to search the code of existing pages on the
> web.

My understanding of that description  when it's contained inside the  
<object> element  is that it should be an equivalent content.  In  
other words, the meaning of the document should not be lost on a user  
who is unable to consume the primary content. This could be  
potentially lengthy. This description might be semantically rich (in  
other words the entire <body> elements content model is available to  
the author). If it is very long then there may be a need, just as  
with the <img> element, to provide a brief description.

As Gregory described:
<http://lists.w3.org/Archives/Public/public-html/2007Jul/0688.html>
> @alt and @longdesc provide distinct purposes:
>
> 1. alt text enables the user who -- for whatever reason -- cannot
> process images (text-only browser, for example); often the alt
> text is not an exact duplication of the graphic (say a mailbox)
> but a description of what the iconic link will do when activated
> (in the case of the mailbox example, i would never encourage
> anyone to use alt="mailbox" but rather, alt="Send Email to Webmaster"
>
> 2. the purpose of long description is to provide an equivalent
> user experience if a user cannot -- for whatever reason -- cannot
> process the image, especially when that image is part of the
> illustrative content of a page; longdescriptions can be brief
> and to the point (the icon shows the word Valid XHTML with a
> red check-mark next to it, indicating that it has passed
> validation) -- there is no law that says someone must read the
> entire contents of the longdesc -- they are free to read what
> portion of the longdesc they find most germane, which is why
> verbosity in longdesc isn't a problem, in as much as the reader
> can either decide to get more granular information by listening
> to/reading/feeling the entire longdesc, or can simply stop
> listening and return to the document in which the longdesced
> image is located, if the user feels that the portion of the
> long description heard/read/felt is sufficient, then he or she
> is free to return to the document instance in which the image
> being described is located.

If these same principles should not be applied to <object> then I  
could understand that. However, the only reason I can think of (and  
I'm asking for help here in understanding the objections) is that  
@longdesc is simply more difficult for authors and users to use  
(compared to <object> contents). Is it that @longdes either requires  
a separate round-trip to the server or instead, deployment of CSS or  
DOM calls to deal with concealing the local document fragment until  
that fallback is requested by the user agent or the user directly. Is  
that what everyone feels about this. Then just say so. Then I'll know  
you're understanding what I'm talking about, and we can stop beating  
the dead horse as Jon put it.

I'm not trying to introduce simply a long v. short distinction (I do  
think its already being made). I'm trying to ask whether the  
difference between @alt and @longdes on <img> is a useful enough  
distinction, (i.e., they each provide, or could potentially provide,  
a useful facility to authors and users) to justify including @alt  
(the brief alternate as Gregory put it) on other embedded content.

Take care,
Rob
Received on Sunday, 15 July 2007 04:30:57 GMT

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