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Re: Data blocks, not marked up content

From: Ivan Herman <ivan@w3.org>
Date: Fri, 7 Oct 2011 09:26:57 +0200
Cc: Gavin Carothers <gavin@topquadrant.com>, public-html-data-tf <public-html-data-tf@w3.org>
Message-Id: <AF58C992-5EF0-43B1-966F-D59497CA74A4@w3.org>
To: Jeni Tennison <jeni@jenitennison.com>

On Oct 6, 2011, at 21:29 , Jeni Tennison wrote:

> Thanks Gavin,
> On 4 Oct 2011, at 20:30, Gavin Carothers wrote:
>> One of the use cases for both Microdata and RDFa (but not
>> microformats) is the exchange of data that is NOT displayed. Perhaps
>> they should not try and meet this use case.
> I agree this looks like something that users are likely to come up against and that there are several approaches for how they might handle the requirement:
>  * use empty <div>s and <span>s (and other elements) in the body of the page -- empty <a> elements are bad for accessibility iirc

... or using a style="display:none" with real content (for properties).

>  * use microdata/RDFa markup in the head of the document (which has limitations because of the lack of nesting of <meta> elements, though see [1])
>  * include the data in an alternate syntax (Turtle / RDF/XML / microdata+json etc) within <script> elements in the <head> as you suggest
>  * link to an alternative format through rel="alternate" <link> element with an appropriate type to indicate the format
>  * use AJAX requests to pull in data in other formats as required

The microdata spec also allows, afaik, the <link> and <meta> elements in the body if used with microdata attributes. Which is a good approach. I would like to see that possibility extended to RDFa, too. The simplest approach would be to allow <link> and <meta> in the body in general. The RDFa processing model would handle those out of the box.

Maybe this is a recommendation this group could make to HTML5



> Would you be able to write this up within the wiki at [2], do you think, with your example? In particular, it would be good to answer the question of when it *is* a good idea to embed data within HTML rather than embedding/linking off to data in a different format. For example:
>  * accessible by consumers that understand embedded markup but not other formats
>  * drag/droppable along with content
>  * if there's other markup in the page about these things, using it for hidden data is consistent
> Thanks,
> Jeni
> [1]: http://www.w3.org/Bugs/Public/show_bug.cgi?id=14112
> [2]: http://www.w3.org/wiki/HTML_Data_Use_Cases
> -- 
> Jeni Tennison
> http://www.jenitennison.com

Ivan Herman, W3C Semantic Web Activity Lead
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Received on Friday, 7 October 2011 07:25:51 UTC

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