Re: RDFa API - Collections / List

Hi Nathan,

I agree with Ivan's comments, and would also add that the reason we
have avoided putting anything to do with lists and collections into
RDFa is that there is no consensus in the RDF community on the best
way to do them. It would have been very easy to make use of ol, ul and
li...but to generate what? alt, seq and bag are rarely
used...rdf:first, rdf:rest and rdf:nil don't have unanimous's really not clear what we should do.

By the way, the main reason that the RDFa spec talks about triples
being generated in the 'default graph' is to allow for experimentation
to take place by using additional graphs.

So if you wanted to generate rdf:first, rdf:rest and rdf:nil --
perhaps derived from <ol> and <ul> -- then provided your parser placed
these triples into a separate graph it would still be fully
conformant. Obviously you'd need to provide a way for developers to
get those triples, but that wouldn't be that difficult.

(The RDFa API should support this, but there has been some reluctance
to get down to the graph level in the API...we might need to revisit



Mark Birbeck, webBackplane

webBackplane is a trading name of Backplane Ltd. (company number
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On Tue, Oct 12, 2010 at 9:31 AM, Nathan <> wrote:
> Hi Ivan,
> Cool, I can agree with that as it opens up a whole can of worms, if you make
> access to Collections easier / custom, then why not the same for BlankNode,
> and so on and so forth, after implementing it's certainly easier just
> treating the store as a graph of triples, similar to N-Triples.
> Will give some feedback specific to your RDFa Collections proposal under
> separate cover.
> Many Thanks,
> Nathan
> Ivan Herman wrote:
>> Nathan,
>> This is, again, a typical '3rd box' feature, if any. Ie, it should be part
>> of the possible future extensions of a RDF API, but certainly not part of
>> the core RDFa API. In my personal opinion we should not spend energy on that
>> one for now (regardless of the outcome of ISSUE-16), but flag it as a
>> possible future item for RDF API
>> Ivan
>> On Oct 11, 2010, at 21:10 , Nathan wrote:
>>> Hi All,
>>> I've just (about) completed a Turtle parser which has brought the issue
>>> of RDF Collections, specifically Lists, to the forefront of my attention.
>>> Currently I've resorted to taking the N-Triples approach adding the
>>> appropriate series of rdf:first, rdf:rest, rdf:nil to the store - however
>>> I'm very aware that in no way do we mark Collection as being a specific type
>>> of RDF Interface, nor do we provide any way to work with Collections/Lists.
>>> So, in terms of the API, do we want to ignore that Collections even
>>> exist, or do we want to specifically address them by adding an RDFCollection
>>> Interface? (perhaps extending BlankNode and containing a sequence of
>>> RDFNode, the list elements)
>>> Somewhat related to ISSUE-16 .
>>> Best,
>>> Nathan
>> ----
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home:
>> mobile: +31-641044153
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Received on Tuesday, 12 October 2010 09:08:38 UTC