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Re: @rel and @property symmetry

From: Ivan Herman <ivan@w3.org>
Date: Fri, 11 Nov 2011 10:07:51 +0100
Cc: RDFa WG <public-rdfa-wg@w3.org>
Message-Id: <D5E9DA03-5096-4420-B261-2B40B1003287@w3.org>
To: Jeni Tennison <jeni@jenitennison.com>

On Nov 11, 2011, at 24:11 , Jeni Tennison wrote:

> Hi,
> 
> I noticed in the minutes of your meeting today that you talked a bit about symmetry between @rel and @property.
> 
> I did a write-up showing parallel microformats, microdata and RDFa markup recently [1] and without even trying (I didn't pick this case specifically, just selected an example from schema.org randomly) came up against the unwanted chaining issue that Michael Steidl raised last month [2]. The example was to create
> 
> [ a schema:Event ;
>  schema:url <nba-miami-philidelphia-game3.html> ;
>  schema:name " Miami Heat at Philadelphia 76ers - Game 3 (Home Game 1) " ; ]
> 
> with markup like:
> 
> <div about="_:event" vocab="http://schema.org/" typeof="Event">
>  <a rel="url" href="nba-miami-philidelphia-game3.html">
>    <span about="_:event">
>      NBA Eastern Conference First Round Playoff Tickets:
>      <span property="name"> Miami Heat at Philadelphia 76ers - Game 3 (Home Game 1) </span>
>    </span>
>  </a>
>  ...
> </div>
> 
> Note the use of the blank node named _:event in order to bypass the unwanted chaining; I couldn't think of another way of doing it without repeating content (does anyone else have another suggestion?).
> 
> So I'm really pleased to see the adoption of @property *without* chaining, which allows this to be rewritten as:
> 
> <div vocab="http://schema.org/" typeof="Event">
>  <a property="url" href="nba-miami-philidelphia-game3.html">
>    NBA Eastern Conference First Round Playoff Tickets:
>    <span property="name"> Miami Heat at Philadelphia 76ers - Game 3 (Home Game 1) </span>
>  </a>
>  ...
> </div>
> 
> This is a plea to not to make @property always chain: not chaining is useful, and it is a good thing to give a publisher an easy way to do it.

Thank you! This issue was discussed yesterday, and we decided _not_ to provide a symmetry with exactly this type of usage in mind...

> 
> I also support not changing @rel behaviour, both for backwards-compatibility reasons and because although it's useful to have non-chaining behaviour, it is *also* useful sometimes to have chaining. I don't think the lack of symmetry is a problem if you think of @rel as an advanced variant of normal @property behaviour rather than them being synonyms.
> 

I agree

Thanks

Ivan


> Cheers,
> 
> Jeni
> 
> [1] http://www.w3.org/wiki/Mixing_HTML_Data_Formats#Mixing_Syntaxes
> [2] http://lists.w3.org/Archives/Public/public-rdfa-wg/2011Oct/0018.html
> -- 
> Jeni Tennison
> http://www.jenitennison.com
> 
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Friday, 11 November 2011 09:05:24 GMT

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