About: http://webisa.webdatacommons.org/355484159

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	Letters or other pieces of First-Class Mail or Standard Mail may be placed in an envelope and attached to the address side of a Periodicals, Standard Mail, or Package Services piece.
http://www.w3.org/ns/prov#wasQuotedFrom	usps.gov