About: http://webisa.webdatacommons.org/334900658

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	Secondly I suspect Facebook using an AJAX request in the OnUnload event, which basically delays the page close until the script decided whether closing is allowed or not.
http://www.w3.org/ns/prov#wasQuotedFrom	superuser.com