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Re: Exact wording for non-prefixed CURIEs in @rel/@rev

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Tue, 22 Jan 2008 15:44:43 -0500
Message-ID: <479655BB.3010602@digitalbazaar.com>
To: RDFa <public-rdf-in-xhtml-tf@w3.org>

Mark Birbeck wrote:
> Now...sorry to keep repeating the same point, but the issue has never
> been about how to recognise the reserved values, but how to *ignore*
> the non-recognised values. In your model a value of "foo" will be
> processed as a non-prefixed CURIE, and so generate a triple.

That's fine - it's a valid point. :)

I don't know what is in the current editors draft, but from what Shane
wrote, he had the following two lines in his text:

# the mapping to use when there is no prefix is the URL for the XHTML
  vocabulary definition, http://www.w3.org/1999/xhtml/vocab#;
# a mapping to use when there is no prefix (for example, next);

I don't think we should have a "mapping" to use when there is no prefix.
The two lines above should be removed from the document. Having a prefix
mapping for non-prefixed CURIEs assumes that all non-prefixed CURIEs are
valid and have a mapping (which is not true).

Only non-prefixed CURIEs defined in the XHTML+RDFa spec are allowed, all
others will not generate namespaced predicates, thus MUST NOT generate
triples.

Current issues with this proposal:
   * Shane mentioned that these same rules should apply to @property.
     Was that what the consensus was? I think it should, for
     consistency.
   * Shane also mentioned that we don't use the term "namespace" when
     talking about prefix-mappings, but if we get rid of the "no prefix"
     mapping, what do we call it? I'm going to continue calling it a
     namespace until there is a suitable replacement (that isn't
     "mapping")
   * Mark, Shane, does getting rid of the "no prefix" mapping screw
     anything else up?
   * If we put these rules in there, should we get rid of the colon-only
     CURIE form (ie... ":next")?

Here's the second attempt, changes highlighted in **

---------------------------------------------------------------------------

===== Section 9.2.6.1: Processing non-prefixed CURIEs in @rel/@rev

A CURIE is considered a 'non-prefixed CURIE' if there is no namespace
defined and no preceding colon. An example of a 'non-prefixed CURIE' is
rel="next" or rev="glossary". To provide compatibility with current
semantics expressed in XHTML documents, certain non-prefixed CURIEs MUST
set the predicate for generated triples when used in @rel and @rev.

These non-prefixed CURIEs are:

alternate, appendix, bookmark, chapter, contents, copyright, glossary,
help, icon, index, meta, next, p3pv1, prev, role, section, subsection,
start, and up.

When processing these CURIEs, the parser must prepend the
http://www.w3.org/1999/xhtml/vocab# namespace to the beginning of the
'non-prefixed CURIE' in the generated triple. For example, rel="next"
becomes http://www.w3.org/1999/xhtml/vocab#next in the generated triple.
To illustrate,

<a rel="next" href="http://example.org/page2.html">

should generate the following triple:

<>
   <http://www.w3.org/1999/xhtml/vocab#next>
      <http://example.org/page2.html> .

*******************
Any 'non-prefixed CURIE' that is not listed above MUST NOT have the
http://www.w3.org/1999/xhtml/vocab# namespace pre-pended to it, thus the
value MUST NOT be used when generating a triple.
*******************

===== Section 5.3, Step #4 (addition):

'Non-prefixed CURIE's are processed by prepending the
http://www.w3.org/1999/xhtml/vocab# prefix to each predicate that is
a recognized 'non-prefixed CURIE'. A list of all valid non-prefixed
CURIEs is available in Section 9.2.6.1.

**************
Any 'non-prefixed CURIE' that is not recognized will not generate a
valid URI and thus MUST be ignored by the parser as if the value was
never specified.
**************

---------------------------------------------------------------------------

Thoughts?

-- manu

-- 
Manu Sporny
President/CEO - Digital Bazaar, Inc.
blog: Intro to the Semantic Web in 6 minutes (video)
http://blog.digitalbazaar.com/2007/12/26/semantic-web-intro
Received on Tuesday, 22 January 2008 20:44:51 GMT

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