FIM-flight interruption manifest, a blank check to another airline. Very 1990's. Your travel agent or UA will most likely nor use one, they will simply exchange your ticket. Is your travel agent an old timer who learned the job decades ago and hasn't kept up with the changes to the industry? Some carriers still issue FIMs a lot, but very few us carriers do, as they ate an accounting nightmare are fraud with them is very easy. They actually look like a check and are filled out the same way, with numbers, then the numbers spelled out in block letters. I.e. O N E- P A S S E N G E R