About: http://webisa.webdatacommons.org/454642904

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	XS is a (phonetic?) acronym for eXternal Subroutine, where external means external to Perl, i.e. written in some other language, such as C or C++.
http://www.w3.org/ns/prov#wasQuotedFrom	std.com