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Issue http://www.w3.org/2000/03/rdf-tracking/#rdf-ns-prefix-confusion

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Thu, 17 May 2001 16:38:16 +0100
To: w3c-rdfcore-wg@w3.org
Message-ID: <24664.990113896@tatooine.ilrt.bris.ac.uk>

Here is a second attempt at rewording previous things from earlier
discussions and resolutions, firstly I'll review what we resolved 

First resolution interpretation 1) in
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001May/0035.html
and second resolution items 1-4
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001May/0036.html
was agreed as recorded in the minutes of the 2001-05-11 meting:
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001May/att-0060/01-2001-05-11.html


Summarising and rewording the above.  I propose we resolve:

1.  The current RDF/XML syntax uses the following attributes
    in the syntax (from my reference at
    http://www.redland.opensource.ac.uk/notes/concepts.html )

    List of RDF attributes (henceforth The List)
      about aboutEach aboutEachPrefix
      ID bagID resource parseType 
      li <_n>
      subject predicate object type value

    Discussion:
    ISSUE: I propose we do NOT add the remaining concepts:
      Seq Bag Alt Property Statement
        - these are rdfs:Class-es and can never be used as attributes
      RDF Description   
        - syntax only things that have no current use as attributes


2.  The grammar will be corrected to require namespace-qualification
    for all attributes for The List.  A namespace prefix MUST be used
    for these attributes, where the namespace prefix points to the
    RDF URI http://www.w3.org/1999/02/22-rdf-syntax-ns#

    The meaning of the attributes is defined by the appropriate RDF
    M&S sections and is not modified here.

    The changes to the grammar at
      http://www.w3.org/TR/REC-rdf-syntax/#grammar
    include modifying productions 6.6, 6.7, 6.8, 6.9, 6.11, 6.18,
    6.32, 6.33 to have rdf: added before all the attributes.  There
    are almost certainly other changes to the grammar, as well as
    changes throughout the rest of the document such as examples and
    in-text mentions.

3.  On input, processors MUST accept unprefixed attributes from The
    List on any elements.  These attributes must be processed
    as if they were written with a prefix as defined in #2.

4.  On output, processors MUST emit attributes from The List
    with a namespace prefix; where the prefix is defined as in #2.

5.  The unprefixed attributes are deprecated and MAY be forbidden in
    future versions of the syntax.

    Discussion: We may suggest that processors could emit a warning
    on input optionally.

6.  The grammar will be corrected to allow non-namespace
    qualified RDF elements (NOT attributes) when a default XML
    namespace is defined with an xmlns="..." attribute.

    Discussion: For example
      <Description xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
        ...
      </Description>
    is currently forbidden by production 6.3; it requires rdf:Description

7.  Unprefixed attributes not on The List have no meaning in RDF
    and MUST NOT be used to generate statements.   Processors MUST
    also skip the element containing such attributes and generate no
    statements for the entire XML element and content.

    Discussion:
    This is consistent with existing words in RDF M&S describing
    actions when unknown rdf: attributes are found:

      [[ When an RDF processor encounters an XML element or attribute
      name that is declared to be from a namespace whose name begins
      with the string "http://www.w3.org/TR/REC-rdf-syntax" and the
      processor does not recognize the semantics of that name then
      the processor is required to skip (i.e., generate no tuples
      for) the entire XML element, including its content, whose name
      is unrecognized or that has an attribute whose name is
      unrecognized.]]
      -- http://www.w3.org/TR/REC-rdf-syntax/ section 6


Some test cases of how the proposed change would work

Test Case 1
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001May/att-0070/01-rdf-ns-prefix-confusion-2.rdf
MUST return two statements (s,p,o form):

  (http://foo,  rdf:type, http://example.org/Class)
  (http://foo,  http://example.org/property, "bar")

Test Case 2
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001May/att-0070/02-rdf-ns-prefix-confusion-3.rdf
MUST return the same two statements.


I'm working on individual tests for each attribute on The List but I
want confirmation it is the definitive list.

Dave
Received on Thursday, 17 May 2001 11:38:18 EDT

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