About: http://webisa.webdatacommons.org/261247847

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	Now, considering your main concern which is that an attacker could build a list of the registered usernames on your website, there is a solution to mitigate this problem.
http://www.w3.org/ns/prov#wasQuotedFrom	stackexchange.com