About: http://webisa.webdatacommons.org/358858006

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	@NullUserException - I do not keep up with this portion of the spec really, some of the regex guys might...but that article is a few years old, though it is the same bug as the OPs seeing.
http://www.w3.org/ns/prov#wasQuotedFrom	stackoverflow.com