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Re: Microdata implied property order

From: Bob Ferris <zazi@smiy.org>
Date: Thu, 20 Oct 2011 10:44:48 +0200
Message-ID: <4E9FDF80.3010309@smiy.org>
To: public-html-data-tf@w3.org
Hi,

[snip]

>  > For example (from schema.org):
>  >
>  > <div itemscope itemtype="http://schema.org/MusicPlaylist">
>  > 1. <div itemprop="tracks" itemscape
> itemtype="http://schema.org/MusicRecording">...</div>
>  > 2. <div itemprop="tracks" itemscape
> itemtype="http://schema.org/MusicRecording">...</div>
>  > </div>
>
> s/itemscape/itemscope/
>
>  > There is an assumed ordering of the tracks in a playlist, but no
> clear processing rules (for RDF anyway) to describe the ordering. With
> previously existing rules, this would render the following:
>  >
>  > @prefix : <http://schema.org/> .
>  > [ a :MusicPlaylist
>  > :tracks [ a :MusicRecording; ...], [a :MusicRecording; ...]
>  > ]
>
> Yes. I think it should be:
>
> @prefix : <http://schema.org/> .
> [ a :MusicPlaylist ;
> :tracks (
> [ a :MusicRecording; ...]
> [ a :MusicRecording; ...]
> ) ;
> ]
>
>  > RDFa recently added the @inlist attribute to indicate that property
> values should be added to a list, so the same thing could be represented
> as follows:
>  >
>  > <div vocab="http://schema.org/" typeof="MusicPlaylist">
>  > <div rel="tracks" inlist>
>  > 1. <div typeof="MusicRecording">...</div>
>  > 2. <div typeof="MusicRecording">...</div>
>  > </div>
>  > </div>
>
> Or:
>
> <div vocab="http://schema.org/" typeof="MusicPlaylist">
> 1. <div rel="tracks" inlist><div typeof="MusicRecording">...</div></div>
> 2. <div rel="tracks" inlist><div typeof="MusicRecording">...</div></div>
> </div>
> </div>
>
> where the parallels with the microdata equivalent are a little more
> obvious.
>
>  > which would render the following:
>  >
>  > @prefix : <http://schema.org/> .
>  > [ a :MusicPlaylist
>  > :tracks ([ a :MusicRecording; ...] [a :MusicRecording; ...])
>  > ]

For representing ordered lists in RDF, I co-designed some time ago the 
Ordered List Ontology [1], which enables a utilisation of existing items 
(resources), as it is the case in the music playlist example above, by 
not including position information into the item object (i.e. there are 
separate slot objects that enclose the item objects).
For addressing the music playlist, one could then utilise a 
specialisation of the ordered list concept, which is called 'playlist' 
[2]. To get an impression how such an example looks like, please have a 
look at [3].
I guess, one can adapt the ordered list concept to microdata and RDFa as 
well (incl. some inbuilt mechanism to simplify the mark-up).

Cheers,


Bo


PS: rdf:Lists are not really appropriated, because we not intend to 
modell a music playlist with a list of lists of lists (what's the case 
of the rdf:List recursion)


[1] http://purl.org/ontology/olo/core#
[2] http://purl.org/ontology/pbo/core#Playlist
[3] http://purl.org/ontology/pbo/playbackontology.html#sec-playlist-example
Received on Thursday, 20 October 2011 08:45:22 GMT

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