I respectfully disagree. The official SEC (not FIN
Post# of 72440
https://www.sec.gov/data/foiadocsfailsdatahtm
“In a “naked” short sale, the seller does not borrow or arrange to borrow the securities in time to make delivery to the buyer within the standard three-day settlement period.[3] As a result, the seller fails to deliver securities to the buyer when delivery is due ( known as a “failure to deliver” or “fail” ).”
https://www.sec.gov/investor/pubs/regsho.htm