query is an xs:string constrained by the language definition,
http://www.w3.org/TR/rdf-sparql-query/#grammar, as "a sequence of characters in
the language defined by the [SPARQL] grammar, starting with the Query production"
The type for serializing query results, either as XML or RDF/XML.
This element contains human-readable information about the fault returned by
the SPARQL query processing service.