About: http://webisa.webdatacommons.org/196551188

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	In addition, in the projection type, in order for an image to be formed so as to have a focus far ahead, an optical system such as a lens or a mirror will become necessary.
http://www.w3.org/ns/prov#wasQuotedFrom	freepatentsonline.com