About: http://webisa.webdatacommons.org/452225498

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	Since reference types are null if not present, that lets you know right away if a DateTime was present or not (because the encapsulating reference type would be either non-null or null.)
http://www.w3.org/ns/prov#wasQuotedFrom	stackoverflow.com