On rare occasions during the RTTY Roundup I copied running stations on FT4 sending messages beginning with TU; and then continuing with the exchange for the next station. I even found myself sending this once or twice. It was very helpful, and dealt well with the usual difficulty the search-and-pounce station has determining whether or not the QSO was completed successfully.
But I don't know when it happens and I could find no mention in the User Guide.
Can anyone enlighten me? It would be very useful if something like this was sent at the end of every QSO in all the contest modes.