Used for listed equity securities. "Go to the floor and check with the specialist or floor broker that my previously active order has been cancelled and was not executed ". One does not have to honor any trade reported after given a "firm out".
"CONFIRM ME OUT"
Meaning of "CONFIRM ME OUT" in English
Campbell R. Harvey. Hypertextual finance English glossary. Английский словарь гипертекстовых финансов. 2012