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Re: [RDFa] ISSUE-3 @class and @role for rdf:type

From: Ben Adida <ben@adida.net>
Date: Thu, 28 Jun 2007 07:14:59 -0700
Message-ID: <4683C263.8000204@adida.net>
To: Ivan Herman <ivan@w3.org>
CC: mark.birbeck@x-port.net, RDFa <public-rdf-in-xhtml-tf@w3.org>, SWD WG <public-swd-wg@w3.org>


It's important to remember that we agreed that it is too late to change
@class, since we've published many talks and documents that use it. I
would strongly vote for not revisiting this. Having an additional
attribute may be okay to provide an alternative for folks who find
@class distasteful, but I'm not hugely in favor of it (one way is better
than two.)

-Ben

Ivan Herman wrote:
> Mark,
> 
> as I said: I am not sure about the usage of @role, I did not follow the
> details of that. I am happy to disregard @role for now.
> 
> I also agree that rdf:type is important, so it is probably a good idea
> to give a shorthand (just like Turtle does). @isA sounds perfectly fine
> to me...
> 
> Ivan
> 
> Mark Birbeck wrote:
>> Hi Ivan,
>>
>> I also prefer a new attribute.
>>
>> The only thing I feel really strongly about is that we don't use @role
>> for rdf:type, since I think that will come back to bite us in the
>> future. So for me, that leaves two choices, use @class or use a new
>> attribute.
>>
>> I can live with using @class, but I do agree that it comes with some
>> baggage. I don't mean that from the point of view of some kind of
>> 'backlash', since I think people are using @class semantically already
>> (even without using microformats). What I mean is that I can easily
>> imagine people forgetting to put foaf:Person (for example) in the
>> class attribute on the containing element, since novice authors would
>> probably see it as 'I must set the CSS class to foaf:Person for this
>> to work'.
>>
>> I also believe that rdf:type is so important that it should be part of
>> the core RDFa attributes, that are independent of any host language. A
>> host language may have an additional way of doing this, and we might
>> even decide in the future to use @class in HTML after all. But by
>> having our own attribute, it means that there is a core way of marking
>> up rdf:type that is always there, no matter what language is the host.
>>
>> So to summarise; my preferred approach would be to leave @class
>> undefined for now--we can always come back to this in a future
>> version--and use @isA or something like that, to indicate the rdf:type
>> of something.
>>
>> Regards,
>>
>> Mark
>>
>>
>>
>> On 28/06/07, Ivan Herman <ivan@w3.org> wrote:
>>> I am a bit uneasy with the usage of @class. _I know_ that the formal
>>> semantics of @class allows this type of usage, and I also know that the
>>> microformat community uses that trick, I still feel that usage @class is
>>> putting a semantics into the attribute that a lambda user would not
>>> expect. (And yes, I am also uneasy with the way the microformats reuse
>>> attributes like title, class, or abbr...).
>>>
>>> I would prefer to use a dedicated attribute if we need it (or simply
>>> stick to the rel="rdf:type", which is at disposal anyway).
>>>
>>> I must admit I am not fully familiar with the discussion behind @role to
>>> decide whether @role should be introduced in RDFa for XTHML1, too, to
>>> cover this usage, or whether a different @type or similar should be
>>> introduced. I guess this discussion should start _if_ ISSUE-3 is not
>>> resolved for @class
>>>
>>> Ivan
>>>
>>> P.S. Having said all that: I do not consider this issue as life
>>> threatening:-) Ie, resolving it quickly is probably more important than
>>> spending lots of time finding the best solution.
>>>
>>> Ben Adida wrote:
>>>> Another issue up for discussion.
>>>>
>>>> ISSUE-3
>>>> http://www.w3.org/2006/07/SWD/track/issues/3
>>>>
>>>> The question is what @class and @role should yield in XHTML1.1+RDFa. We
>>>> don't have complete consensus on this (we specifically note Steven
>>>> Pemberton's worries about the reuse of the @class attribute), but the
>>>> current solution, as accepted in the Primer and in many use cases,
>>> is as
>>>> follows:
>>>>
>>>> @class yields rdf:type only if the value is namespace-qualified. @class
>>>> contains a space-separated list of values. Only those values which are
>>>> namespace-qualified yield rdf:type triples.
>>>>
>>>> @role does not exist in XHTML1.1, so it is not used here. In XHTML2, it
>>>> is expected to yield a triple with predicate xhtml2:role.
>>>>
>>>> +1 if you agree, otherwise email your disagreements and explanation.
>>>>
>>>> -Ben
>>>>
>>> -- 
>>>
>>> Ivan Herman, W3C Semantic Web Activity Lead
>>> URL: http://www.w3.org/People/Ivan/
>>> PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html
>>> FOAF: http://www.ivan-herman.net/foaf.rdf
>>>
>>>
>>
> 
Received on Thursday, 28 June 2007 14:15:21 UTC

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