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ISSUE-70: Formal Response

From: Shane McCarron <shane@aptest.com>
Date: Fri, 18 Feb 2011 15:13:59 -0600
Message-ID: <4D5EE117.3020807@aptest.com>
To: RDFa WG <public-rdfa-wg@w3.org>, Jeni Tennison <jeni@jenitennison.com>
Jeni,

Thanks for your detailed comment captured in the RDFa Working Group's 
issue number 70 (http://www.w3.org/2010/02/rdfa/track/issues/70).  The 
working group has reviewed this comment in the context of the many other 
last call comments we received.  Our responses are provided inline:

> So to the first, large, technical point: the lack of information about
> versioning. Having read through the RDFa Core LC WD and the XHTML+RDFa
> LC WD, I can't see anything that addresses versioning except for the
> removal of the version attribute (which was the mechanism for
> indicating the version of RDFa being used provided by RDFa 1.0).
>
> There are a number of backwards-incompatible changes in RDFa 1.1, some
> of which are called out in Appendix C.1 [1], such as:
>
> * the introduction of the prefix attribute
> * the introduction of terms and profiles
> * the interpretation of complex content lacking an explicit datatype
> as a plain literal rather than an XML literal
>
> As someone managing a large site that produces RDFa, the questions I
> need answered are:
>
> 1. What are the minimal steps I need to take to ensure that my RDFa
> 1.0 site continues to be interpreted in the same way by an RDFa 1.1
> processor?

We will expand the text in Appendix C so that there is guidance on this. 
  We will also add a requirement that conforming processors MUST support 
RDFa 1.0 - style processing when presented with the @version value that 
was specified in RDFa Syntax [1].  Consequently, there are two things 
you can do to achieve this goal.  First, you can put version="XHTML+RDFa 
1.0" on the html element of the documents your site delivers.  Second, 
you can set @datatype="rdf:XMLLiteral" anywhere you actually want an 
XMLLiteral generated instead of a plain literal, and @datatype="" 
anywhere you want a plain literal.  Note that if you do need to 
reference rdf:XMLLiteral, you will of course need to define the rdf 
CURIE prefix using xmlns:rdf.

> 2. When I move to using RDFa 1.1, how do I ensure that my site is
> interpreted in the same way by an RDFa 1.0 processor as it is by RDFa
> 1.1 processors?

In general, you cannot.  If you are using RDFa 1.1 features, those 
features are not going to be available in an RDFa 1.0 processor. 
However, if your goal is to ensure the most compatibility with 1.0 
processors, there are some things you can do on your site.  We will 
describe these in Appendix C as well.  Essentially, you need to avoid 
using any RDFa 1.1 features, set datatype="rdf:XMLLiteral" if you want 
an XMLLiteral, and datatype="" if you want a plain literal.  You will 
also want to ONLY use TERMs that were defined in RDFa Syntax 1.0 as 
"RESERVED WORDS" for values of @rel and @rev.  To future-proof your 
site, you will probably also want to use @prefix and @xmlns:foo everywhere:

    <div xmlns:foo="http://www.example.com" prefix="foo:
    http://www.example.com"



>
> As a developer of an RDFa processor, the questions I need answered are:
>
> 3. Can my processor be both a conformant RDFa 1.0 processor and a
> conformant RDFa 1.1 processor?

The short answer is "yes".  We will add text about this in the section 
on RDFa Processor Conformance.  In addition, in order to improve the 
story about this going forward, we will introduce another RDFa 
attribute, @rdfa, which will can be used by documents that wish to 
ensure their content is interpreted against a specific version of the 
RDFa Recommendation(s).

The rules such a processor must follow are:

   1. If there is an @rdfa attribute on the root element of the
      document, examine its value.  If the value maps to a defined
      version string for RDFa, process the document according to that
      version's rules.
   2. If there is an @version attribute on the root element of the
      document, and that attribute has the value "XHTML+RDFa 1.0",
      process the document according to the rules from RDFa Syntax 1.0
      (for backward compatibility).
   3. Otherwise, process the document according to the rules defined in
      this specification (RDFa Core 1.1).

Note that there is no REQUIREMENT that a document use this announcement 
mechanism.  It is just available.  In the absence of any sort of 
announcement, the default behavior is to use the current best practice 
as defined in the current version of RDFa.

> 4. If not, what modes of processing do I have to offer in order to
> best enable users of the processor to correctly interpret RDFa 1.0 and
> RDFa 1.1 web pages in the way their authors intended?

See above.

The working group hopes that these comments and changes will address 
your Last Call comment.  Please respond to this mail at your earliest 
convenience.

[1] http://www.w3.org/TR/rdfa-syntax/

-- 
Shane P. McCarron                          Phone: +1 763 786-8160 x120
Managing Director                            Fax: +1 763 786-8180
ApTest Minnesota                            Inet: shane@aptest.com
Received on Friday, 18 February 2011 21:15:13 UTC

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