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Re: RDFa - Dublin Core Metadata - [Fwd: Draft of revised version of Expressing DC in X/HTML meta/link elements]

From: Ivan Herman <ivan@w3.org>
Date: Thu, 09 Aug 2007 16:20:08 +0200
Message-ID: <46BB2298.7010400@w3.org>
To: Mark Birbeck <mark.birbeck@formsPlayer.com>
Cc: W3C RDFa task force <public-rdf-in-xhtml-tf@w3.org>

Mark Birbeck wrote:
> Hi Ivan,
>> Personally, I think we should define a @profile.
> I thought we'd resolved to create a profile, but to make it optional.
> That allows those who want to be able to say "my document definitely
> contains RDFa" to do so, at the same time as aloowing those who want
> to say "I'm going to process every document as if it contains RDFa" to
> also do so.

I know we had that discussed, I did not realize that is a formal
decision now. If so, fine!

>> - There is a small remark on the <meta> element. Essentially, the issue
>> is that @name is used for what we use as @property elsewhere. I wonder
>> whether it would not be possible (and very simple) to allow for @name as
>> an alias to @property in the context of a <meta> element and use it
>> accordingly. This is not unlike what we do with @src for <img>...
> Both should be allowed already, but I don't think we've ever discussed
> it. And I know for sure that we've never said what would happen if
> both attributes were present.

Just as @resource has a higher priority than @href (and @src), I would
say @property has a higher priority than @name.

>> - The most controversial issue, just raising it (please, do not eat me
>> alive here). The syntax used in a <link> @rel is the dotted notation.
>> Ie, dcterm.title. The also use <link> to, essentially, _declare_ those
>> prefixes.
>> We use dcterm:title because, well, we use namespaces. Hm, we use the
>> _syntax_ of namespaces, but we do _not_ use them in the XML sense,
>> right? More as a concatenation sense like in RDF. So, well, can we
>> reconcile these two syntaxes? To be able to handle quite a lot of
>> information out there in terms of DC already? Or to come?
> I think you are right. We've discussed a number of different ways to
> allow support for alternative namespacing mechanisms in the CURIEs
> syntax, but we haven't nailed any down yet. However, so far in this
> group the pain of _not_ having CURIEs doesn't seem to have promoted
> widespread support for it...maybe this is the straw? ;)

I must admit that I am not sure where we stand with CURIE-s at the
moment, I would be pleased if we could clarify this. For all the
examples we have, the following seems to work:

- URI-s in the traditional sense for @href, @src, @resource, just as
XHTML has it
- sort of namespace/qname for @instanceof, @rel, @rev, ...

I think we all agreed that we do not really need that [_:123] type
things. My feeling is: we could drop all this [...] notation once and
for all. I do not see any serious use case; on the other hand, it would
take away a potentially contentious issue...

>> Bear with me:-) I could see the following alternatives:
>> - Accept the a.b notation for @rel, @instanceof, @rev, @property, as an
>> alias to a:b (or a replacement thereof?:-)
> "As well as", is ok, if we have a way of defining it clearly. As I've
> argued before though, "replacement" just seems odd--we have a
> namespacing mechanism in the W3C.

You're right. Let us keep both syntaxes. Ie, in @rel, for example,
dc.author would mean the same as dc:author. I can happily live with
this, and would do a lot ot accomodate the DCMI people...

>> - Accept the special link notation as, essentially, global namespace
>> declarations

What do you think about this?

>> I think we must keep the xmlns notation, because that provides us with
>> the copy paste facilities. But the others, well...
>> Of course, we may ask/hope that the DCMI proposes a namespace-like
>> notation all the way down. I am not sure that would happen.
> CURIEs would help here, since they define a namespacing mechanism that
> stands outside of a document and is independent of languages. (For
> example, CURIEs can be used by SPARQL.)

Mark, I am lost what you mean by CURIE. Where can CURIE-s be used in SPARQL?


> Regards,
> Mark


Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Thursday, 9 August 2007 14:20:06 UTC

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