A double by advancer, after overcall has bid, and after responder has raised opener's suit, is responsive, and shows the unbid suits. It is used ONLY after opponents have found a suit fit. Otherwise, the second double is for penalty.
S: KQJx
H: AJTx
D: x
C: K9xx
S: Axxx
H: Qxxx
D: xx
C: JTx
W N E S
1C X 2C X
3C 4H P/O