About: http://webisa.webdatacommons.org/409666715

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	The cover shall be a substantial material, such as metal or wood, topped with a layer of wetted material to prevent sparks and flames from entering the mine opening.
http://www.w3.org/ns/prov#wasQuotedFrom	ecfr.gov