Most of us just call that 'a transponder' now since, in reality, it isn't *used* for that 'IFF' function anymore (it's early *roots* may have been in that area - but that's been awhile now).
We used to have a poster self-identified as "FormerLurker" who would call it "IFF ..." all the time. Is there a connection here?
Bite you tongue. Absolutely no connection. Even bringing up his name usually results in a several page long cut and paste that bogs threads down to a thick cement even on the fastest systems.
Most military pilots still call it an IFF because that's the role it still performs for us.