Woolsey
Against strong NT:
Double = a mystery 4-card major, and a mystery 5+ card minor (after you play this for a while, you can use the
Tuna fish variation: you also double with a decent 1-suiter in one of the minors)
Over this, 2C says:
pass if your minor is clubs, correct if your minor is diamonds
2D asks doubler to bid his major
2M is natural
2C = both majors (with equal length in the majors, advancer can bid 2D to ask overcaller to pick)
2D = a 1-suiter in one of the majors
2M = at least five cards in that major, and a side minor suit
2N = minors
3m = natural
Woolsey makes it much easier to find your best combined fit. Against that you sometimes end up at the 3-level, and if the opponents bid over the double, it may be hard to compete, since doubler's suits are not known