About: http://webisa.webdatacommons.org/298981236

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	Keep a log of which letter is a copy of which file, but set it up such that you do not know which is which.
http://www.w3.org/ns/prov#wasQuotedFrom	head-fi.org