In effetti sia
www.filext.com/
che
http://file-extension.info/
non riportano XSV nel database delle loro estensioni.....
da
http://66.31.61.166/flogviewer/History.asp :
"Support of XSV file. XSV stand for 'Any-Char' Separated File.
For CSV or XSV file there is now a new filter mode calls 'Where Clause'."