About: http://webisa.webdatacommons.org/23617056

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	transparent central zone, whereby said level or tilt indicator or other instrumentation is visible in the image produced by the optical system.
http://www.w3.org/ns/prov#wasQuotedFrom	docstoc.com