Curious as to what situations those might be? Money is fungible so when would it make sense to leave money on a ticket instead of a refund? The only scenarios I can think of are external to the airline, such as where ticket cost fulfilled a credit card offer or some other payment related situation where you don’t want a refund as it would cause other problems (credit card account closed, etc.). We’re you thinking of something like that or something having to do with the airline and the ticket itself?