OptionalgeneralizedWhether the graph the mapping denotes is a generalized RDF graph, one that admits a literal as a subject and a blank node as a predicate.
Off by default, and a head variable the body could bind outside the range its position admits then costs a type test, since a CONSTRUCT instantiates no triple for a solution that would make an illegal one (SPARQL 1.1 §16.2). Turn it on where the source is read as generalized RDF and those solutions keep their triples; the tests are cheap, but they are wrong for a view that wants them.
What building a mapping may be configured with.