- From: Mark Birbeck <mark.birbeck@x-port.net>
- Date: Thu, 21 Jun 2007 21:41:28 +0100
- To: "Ben Adida" <ben@adida.net>
- Cc: "Ivan Herman" <ivan@w3.org>, RDFa <public-rdf-in-xhtml-tf@w3.org>
Hi Ben, There are two problems with this. The first is that you might not have a @rel value on your <img>. So for example, there may be use cases for the following construct: <img src="my-photo.jpg" class="foaf:Image" /> (Especially since everyone is against the idea of generating a triple for xh:img.) This means that we can't rely on the presence of @rel or @rev to tell us how to interpret @class. The second problem is that as things stand I can't find a justification for applying @class to @href in the way that you seem to be suggesting. The only thing I can find that proposes what @class actually means is in the first link [1] that appears in the page for the issue itself [2]. The post says: --- STARTS --- <div role="wai:toolbar"> ... </div> is equivalent to this: <div> <link rel="xh:role" href="[wai:toolbar]" /> ... </div> To clarify what @class should do, I'm also suggesting that this: <div class="foaf:Person"> ... </div> should be equivalent to this: <div> <link rel="rdf:type" href="[foaf:Person]" /> ... </div> --- ENDS --- Obviously things have changed in relation to '<link> everywhere', since then, but the general point seems relevant. So to use your example: <a rel="dc:creator" href="http://ben.adida.net/#me" class="foaf:Person">Ben</a> the proposal above would have it be equivalent to the following (pretending for a moment that you can have multiple instances of the same attribute, just to make it easier to write): <a rel="dc:creator" href="http://ben.adida.net/#me" rel="rdf:type" href="[foaf:Person]" >Ben</a> I see from your example in a separate thread that when using striping you've suggested that the @class attribute applies to the 'child' bnode, but I find that counterintuitive, and don't recall it being discussed. But either way, I don't see how that applies here, since striping is for when we have a predicate with no @href, and it would obviously be meaningless to have an <img> with no @src (which is what you'd have if you say that @src is the same as @href). I'm not saying by the way that @src on <img> (and <object>) is a 'special case'. I'm simply saying that it has its own defined rules, just like <link>, <meta>, @rel and lots of other things have their own defined rules. The main point I'm driving at is that there doesn't seem much to generalise between @src and @href. Regards, Mark [1] <http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2006Jun/0009> [2] <http://www.w3.org/2006/07/SWD/track/issues/3> On 21/06/07, Ben Adida <ben@adida.net> wrote: > > Mark Birbeck wrote: > > Anyone else have a view? In particular are there any use cases for > > knowing that something is an image, independent of a value in @rel or > > @rev? > > On this issue, I think I agree with Ivan regarding the xh:img triple: it > will seem inconsistent. Why IMG and not OBJECT, TABLE (gasp, tables?), > LINK, SCRIPT, etc..? > > >> Also, are we sure that > >> > >> <s> rdfs:label "alt". > >> > >> is the best representation for this? > > I don't have a strong opinion on this one. > > > Right. That's fine, and I can go either way. The only thing that I > > think we do have to discuss though, is @class. My other proposals are > > about generating 'extra' triples (like 'xyz is an image'), the use of > > @class on an <img> is something that is already allowed, and we > > therefore need to provide an interpretation. > > I agree that we need to provide an interpretation for class="xy:zz" on > an img. I think it's clear that this applies to the IMG, but I think we > don't need to special-case it too much. We've already set the precedent > that @REL automatically sets the subject of all contained triples, > including any triple generated by @CLASS, to be the OBJECT (in that case > a bnode, but the OBJECT nevertheless). I think we can carry this rule > over. If there's a REL on an IMG, then @SRC acts like @HREF and becomes > the subject for all triples generated by contained elements. Thus @CLASS > is the rdf:type of the @SRC attribute. > > I believe this carries over to the following situation involving an > anchor rather than an IMG: > > <a rel="dc:creator" href="http://ben.adida.net/#me" > class="foaf:Person">Ben</a> > > I'm pretty sure that should be interpreted as: > > <http://ben.adida.net/#me> rdf:type foaf:Person . > > right? > > Now, what to do if there is a @REV? I think the same thing applies, > actually, meaning that @SRC is the subject of the @REV predicate, but > *also* of the @CLASS rdf:type and all contained elements. > > One last thing: I think all of above should apply to OBJECT/@SRC. > > > -Ben > > -- Mark Birbeck, formsPlayer mark.birbeck@x-port.net | +44 (0) 20 7689 9232 http://www.formsPlayer.com | http://internet-apps.blogspot.com standards. innovation.
Received on Thursday, 21 June 2007 20:41:37 UTC