In RDF 1.1, there is no longer a difference between simple literals (those
without language or datatype) and literals having a datatype of xsd:string.
From RDF 1.1 Concepts [1]:
[[[
A literal in an RDF graph consists of two or three elements:
• a lexical form, being a Unicode [UNICODE] string, which should be in
Normal Form C [NFC],
• a datatype IRI, being an IRI that determines how the lexical form
maps to a literal value.
...
Concrete syntaxes may support simple literals, consisting of only a lexical
form without any datatype IRI or language tag. Simple literals only exist in
concrete syntaxes, and are treated as syntactic sugar for abstract syntax
literals with the datatype IRI http://www.w3.org/2001/XMLSchema#string.
]]]
I'm trying to reconcile this with the requirements of the SPARQL 1.1 tests,
where there is a difference between a plain literal and one with xsd:string.
For example [2], in this case, STRDT requires that it's argument be a simple
literal, and specifically checks to be sure that literals having a datatype of
xsd:string are excluded from the results:
[[[
PREFIX : <http://example.org/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?s (STRDT(?o,xsd:string) AS ?str1) WHERE {
?s ?p ?o
}
]]]
I realize that SPARQL 1.1 is defined against RDF 1.0, but I wonder if there is
a transition plan, or an alternate set of tests that verify behavior against
RDF 1.1 literal semantics? Or, perhaps I'm misunderstanding something else.
Gregg Kellogg
[email protected]
[1] http://www.w3.org/TR/rdf11-concepts/#section-Graph-Literal
[2] http://www.w3.org/2009/sparql/docs/tests/data-sparql11/functions/strdt03.rq
