About: http://webisa.webdatacommons.org/446720274

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	To avoid shunting the resulting magnetic field, the ground surface may be formed of a less magnetically conductive material, such as low carbon steel, titanium, stainless or other steel, and it may be relatively thin.
http://www.w3.org/ns/prov#wasQuotedFrom	patentlyapple.com