Hell Raises

Here is the list of responses to one of a major:

• 2M: about 6-9 points, exactly 3 trump. Opener can use help-suit game tries, a 2NT asking bid, Mathe Asking Bid, or splinter jumps to help him place the contract.
• 3C: 4+ trump, limit raise strength (including distribution.) Opener can bid 3D as a game try, 3 of the other major to ask for a singleton, or cue-bids, or just bid 3, 4, or 6 of the major.
• 3D: 4+ trump, same strength as single raise (including distribution.) Opener can bid 3 of the other major to ask for a singleton, cue-bid, or bid 3 or 4 of the major.
• 3M: 4 trump, too weak for 3D. Opener can use Mathe or cue-bids, but usually passes (or raises to four with six trump).
• 2S(over 1H), or 3H(over 1S): "Strong splinter" -- 4+ trump, singleton or void in any side suit, enough points to force to game on high cards alone. Opener can ask for a singleton (cheapest step), show a singleton, or bid naturally.
• Double jump shifts: "Weak splinters" -- 4+ trump, singleton or void in bid suit, strength for distributional game, but not enough to force to game on high cards alone.
• 3NT: 4+ trump, balanced hand, game-forcing strength.
• 4M: 5+ trump, weak hand. Usually a distributional feature on the side.

The jump to 2NT is natural and forcing by an unpassed hand (14+ points, balanced, possibly with three trump.) I0-5, 6-9, 10-13, and 14+.