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Re: ISSUE-129 (Power of @vocab): Change the power of @vocab, related to default term interpretation [3rd LC Comments - RDFa 1.1 Core]

From: Niklas Lindström <lindstream@gmail.com>
Date: Fri, 17 Feb 2012 17:05:33 +0100
Message-ID: <CADjV5je94gVXm0L4ZM2WFVNv_44kmq-bpa=7AkuGCa6c9TLxww@mail.gmail.com>
To: Shane McCarron <shane@aptest.com>
Cc: public-rdfa-wg@w3.org
It should also be pointed out that we have a similar usage of
'license' in Core as in the Primer. The example in section "10. RDFa
Vocabulary Expansion" is:

    This document is licensed under the
    <a vocab="http://creativecommons.org/ns#"
       rel="license"
       href="http://creativecommons.org/licenses/by-nc-nd/3.0/">
       Creative Commons By-NC-ND License
    </a>.

I.e. it uses @rel="license" with the clear expectation that @vocab
applies to it.

Best regards,
Niklas

[1]: http://www.w3.org/TR/2012/WD-rdfa-core-20120131/#s_vocab_expansion



2012/2/14 Niklas Lindström <lindstream@gmail.com>:
> Hi Shane, Ivan,
>
> In <http://creativecommons.org/ns#>, cc:license is defined to be
> owl:sameAs xhv:license, and rdfs:subClassOf dc:license. It also has
> rdfs:domain cc:Work and rdfs:range cc:License. So the use of it
> implies an rdf:type for the subject and object as well.
>
> RDFa 1.0 explicitly defined @rel="license" to mean xhv:license.
> Creative Commons are silent on the exact IRI of the predicate when
> used without the 'cc:' prefix though -- they only use the wording "In
> this case, the relationship is "license" -- but as we know they do use
> RDFa.
>
> In general, I'd recommend dc:license, since it is the most general of
> the three. But I would still prefer to allow authors to control this
> with @vocab.
>
>
> To reply to your comments Shane, I'm not sure I understand what you
> mean by this changing randomly? Authors have full control over the
> vocabulary for terms with @vocab (and as we've seen, they have to
> exercise this to manage the situation in <head> and with e.g.
> 'prefetch' or 'nofollow').
>
> Of course, someone may add
> @vocab="http://www.example.org/randomURI/somepage#" to the body, just
> as they might add @prefix="foaf:
> http://www.example.org/stochasticURI/otherpage#". I mean, this is what
> RDFa is about. If you don't control the surroundings of your markup,
> you either have to rely on a contract with the manager of that, or
> explicitly use @prefix, @vocab and/or full IRIs to control your
> properties and types.
>
> I am sympathetic to your appreciation of 'license', but I wonder if it
> really is so generally ingrained in authors that it warrants such a
> special treatment? With my proposal it would still always mean
> xhv:license (or e.g. cc:license if we change it) unless someone
> explicitly uses @vocab (which even so can be reset again with an empty
> value). This is all very dependent on the expectations and background
> knowledge of authors, as well as how vocabulary publishers want @vocab
> to work with their vocabularies. Imagine e.g. if Schema.org mint their
> own IRI for 'license' in the future. (Not that *I* would like that,
> but such is the playing field which I want us to level.)
>
> It is the uniformity of expression in markup like this that I think we
> should value:
>
>    <div vocab="http://purl.org/dc/terms/">
>      <h2 property="title">The Origin of Species</h2>
>      <p>License: <a property="license"
>          href="http://creativecommons.org/licenses/publicdomain/">
>          Public Domain</a>.<p>
>    </div>
>
> Here's another example. I wonder what most people would expect from:
>
>    <dl vocab="http://www.w3.org/2006/vcard/ns#" typeof="VCard">
>      <dt>Name</dt><dd property="fn">Corky Crystal</dd>
>      <dt>Role</dt><dd property="role">Officer</dd>
>      <dt>Email</dt><dd property="email">corky@example.com</dd>
>    </dl>
>
> I really doubt that it's obvious that 'role' in the above actually
> means xhv:role!
>
> For 'role' specifically, I am unable to find where its use as a term
> in the @rel attribute is specified. I find old drafts of it used as
> such in <link> elements in XHTML2, but I thought this was superseded
> by the specific @role attribute used by WAI-ARIA? May it even be that
> we don't need to define 'role' as a reserved term?
>
> Perhaps many authors (and systems) really do expect 'describedby',
> 'license' and 'role' to be fixed to their predefined IRIs even when a
> local vocabulary is active. I only believe that it's just as probable
> that many will not, but will instead expect that @vocab works
> uniformly without special exceptions.
>
> One idea could be to cater for *both* of these expectations. If the
> rules instead were cumulative -- i.e. even if a term mapping is found,
> @vocab would have effect -- then this:
>
>    <a vocab="http://purl.org/dc/terms/" property="license"
> href="/cc-by">CC-BY</a>
>
> would produce *two* statements:
>
>    <> dc:license </cc-by> .
>    <> xhv:license </cc-by> .
>
> At least this way, no information is lost. But it would be really
> gnarly in e.g. the case of the vCard role example above, where the two
> conflicting properties don't even nearly resemble each other. :/
>
> .. Granted, if 'role' *could* be safely removed (leaving only
> 'license' and 'describedby'), and if 'license' was changed to mean the
> very general 'dc:license', I suppose I would be pacified enough even
> without any rule changes. At least if no one else sees this as an
> issue, and assuming nothing like <http://schema.org/license> would
> ever come up as contentious.
>
> Best regards,
> Niklas
Received on Friday, 17 February 2012 16:06:39 UTC

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