About: http://webisa.webdatacommons.org/80400585

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	Of course, realizing this experimentally is a little tricky, but the best clocks do an amazingly good job??? the modern state of the art is good to about a part in 1015, or something like one nanosecond in twenty million years.
http://www.w3.org/ns/prov#wasQuotedFrom	scienceblogs.com