Reifying using XML attributes only

Addressing ACTION: 2001-08-24#8 Dave Beckett
  Write up a proposed resolution for reifying using XML attributes
  anly (sic)


The RDF XML syntax defined in M&S allows properties to be written as
XML attributes in the Qname form, with values that are strings.
These are then turned into RDF statements with a string object.  The
syntax also allows the rdf:type property to be used as an attribute
with the string value interpreted as a URI-reference.

M&S defines explicitly other properties including rdf:subject,
rdf:predicate and rdf:object 
  http://www.w3.org/TR/REC-rdf-syntax/#formalReification

In summary, these take as values:
  Property      Property Value
  --------      --------------
  rdf:type      URI-reference
  rdf:subject   URI-reference
  rdf:predicate URI-reference
  rdf:object    URI-reference or literal

These can be used in this attribute abbreviated form since they match
the grammar propAttr or typeAttr (for rdf:type).

Testing the attached example with parser implementations gives
different results for the statement values - some literals,
some URI-references.

Thus, we need to clarify what is allowed here.


Proposed clarification / resolution, test case.

  For properties encoded in XML attribute form, the attribute value
  is interpreted as a literal for all properties except rdf:type
  for which it is interpreted as a URI-reference.

  The attached N-Triples defines the model produced by the attached
  RDF/XML.


Consequences:
  rdf:subject and rdf:predicate if used in XML attribute form will
  generate literal values which are presently forbidden (I think!)
  or maybe just very unexpected.

  If you want to use rdf:subject, rdf:predicate properties, encode
  them in the property element form (propElt).

  rdf:object can be used but can only take a literal value.

Dave

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