deleting rman data

[<James> <healy>]

i have a question about verifying the deletion of rman data.
i'd like to know how anyone verifies that old versions of rman files are
getting deleted.
My DBAs say they are running the commands to expire old versions but I
don't see it happening
Are there any commands that I could erify this with.
I've checked q occ and the number of files does not decrease for that rman
client.