Weak Two-level Openings

After 2H Ekrens (weak both majors)

New suit Natural, non-forcing but constructive. Opener must act with 3+ fit, and any action implies such fit
Raises Not constructive
2NT Values-based inquiry (a strong response creates a game-force)
3C Weak
3D Game-force shape ask
3H 4S 4-5H (then 3S asks and 3NT shows 4S 4H suit)
3S 5S 4H
3NT 5S 5H
3H Natural, invitational
Natural, invitational
Games To play
3D Strong, 5S 5H
3H Strong, 5H 4S
3S Strong, 5S 4H
3NT Strong, 4S 4H
Games To play
Suit jumps Natural and forcing
In competition, doubles are penalties, and redouble is for rescue.

After the weak 2S opening

This opening bid shows at least five spades, fewer than four hearts, fewer than six of either minor suit and normally less than the values for a one-level spade opening.
2NT Values-based inquiry
3C Any 4-5C
3D/3H Natural and forcing
3S Invitational
3NT To play
4C Sets clubs as trumps and demands control bidding
4D/4H Splinters agreeing clubs
4S/5C To play
3D Any 4-5D
3H/4C Natural and forcing
3S Invitational
3NT/ To play
4D Sets diamonds as trumps and demands control bidding
4H Splinter agreeing diamonds
4S/5D To play
3H No minor, good hand, game-forcing, sets spades unless responder rebids 3NT
3S Shape inquiry
3NT 0-2C
4C 0-2D
4D 0-2H
3NT To play
4C/4D/4H Control bids
4S To play
3S No minor, bad hand, does not set spades
3NT To play
4C/4D/4H Natural and forcing
4S To play
3C/3D/3H Natural and non-forcing, expecting a raise with 3-card or longer fit
3S Not invitational
3NT To play
4C/4D Splinters
4H/4S/5C/5D To play
4NT RKC for spades