_:b21170581	<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>	<mw:File> .
_:b21170581	<http://www.w3.org/2007/05/powder-s#describedby>	<http://dev.restore.ovi.cnr.it:8890/about/id/https/commons.wikimedia.org/wiki/File:Operating_system_placement.svg> .