Where partner opens a major (say S), and overcaller doubles, responder bids 2S with a minimum hand, 3S preemptively, and a Jordan 2NT as a limit raise or better. XX in this position shows 10+ points, and tends to deny opener's suit.
W N E S
X 2N P 4S
Responder would bid 2S with Qxx/Qxx/Kxxx/xxx, 3S with
Qxxx/xxx/Kxxxx/x, and XX with Qx/Qxxx/KQx/Axx.