<http://www.w3.org/2006/http-header#optional>	<http://www.w3.org/2000/01/rdf-schema#label>	"Optional"@en .
<http://www.w3.org/2006/http-header#optional>	<http://www.w3.org/2000/01/rdf-schema#comment>	"The Optional header"@en .
<http://www.w3.org/2006/http-header#optional>	<http://www.w3.org/2007/05/powder-s#describedby>	<http://demo.openlinksw.com/about/id/entity/http/www.w3.org/2006/http-header> .
<http://www.w3.org/2006/http-header#optional>	<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>	<http://www.w3.org/2002/07/owl#Thing> .