_:vb50791025	<http://www.w3.org/2007/05/powder-s#describedby>	<http://demo.openlinksw.com/about/id/entity/urn/r2rml:qa:nfl:1> .
_:vb50791025	<http://www.w3.org/ns/r2rml#constant>	<http://demo.openlinksw.com/schemas/nfl/ischallenge> .