_:vb50809450	<http://www.w3.org/ns/r2rml#column>	"IsChallenge" .
_:vb50809450	<http://www.w3.org/ns/r2rml#datatype>	<http://www.w3.org/2001/XMLSchema#boolean> .
_:vb50809450	<http://www.w3.org/2007/05/powder-s#describedby>	<http://demo.openlinksw.com/about/id/entity/urn/nfl:mapping> .