About: http://webisa.webdatacommons.org/54793012

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	This means that you can compare its value to IS NULL. Here is an example:
http://www.w3.org/ns/prov#wasQuotedFrom	functionx.com