Opener has started with a strong 1♣ and direct seat cheekily bids something at the 2 level. This system attempts to improve on "X shows 5-7" which seems to show too little shape and make constructive bidding difficult.

The basic premise is that we assume Opener has the most common hand: 17-19 balanced, but we have to make allowances for both weak (in the context of a 1♣ opener!) shapely hands and strong hands.

What Did They Show?

We divide the world into situations where the opponents have shown nothing (e.g. CRASH, Suction), one known suit, or two known suits.

Vs. Two Known Suits

When they have shown two known suits, we like to play Unusual vs. Unusual. Double is still penalty oriented, but creates a game force. If they might have only 4 cards in one of their suits, we should be open to the possibility of eventually using that as our trump.

Bidding a suit directly shows 5-7, and cue bidding a known opponent suit shows 8+.

Vs. Zero Known Suits

When they have made a conventional overcall like CRASH or Suction where the first call doesn't really say what suit the overcaller has, the Opponents are nearly guaranteed to make another call; also it is difficult for Advancer to raise immediately to a high level because Advancer also doesn't know what Overcaller has. Therefore, there is less pressure for us to get our semi-positive strength going.

Responder's new suit is natural and GF. Double is GF "without clear direction"; implying balanced, 4x1, or occasionally with a 5 card suit to embarrassing to mention. Responder's Jump shows 5-7 with a decent six card suit (at least AT or KJ). NT should show 12+.

One Level Interference

At the one level, we have more space to work with, and also it is less interesting to try to stop for penalties. Generally Responder makes a negative free bid at a low level or a GF bid at a higher level.

Pass - 0-4 HCP or trap pass. Promise 3+ clubs over 1♣X.
XALERT - 5-7 HCP balanced. May or may not have stoppers.
XXALERT - same as X
1♦ALERT - 0-4 HCP, 0-2 clubs.
non-jump majorALERT - 5+ cards, 5-7 HCP
2mALERT - 6+ cards, no 4 card major, 5-7 HCP
1NTALERT - unbalanced, one or two 4 card majors, 5-7 HCP (or at least 5-4 minors)
2Q - GF without clear direction
jump new suit - 5+ suit, 8+ GF
3Q - strong three suiter
2NT - 8-11 or 15+ balanced, stoppers. 2NT systems on
3NT - 12-14 balanced, stoppers. 2NT systems on

Further Bidding by Opener

After negatives (Pass or 1♦), Opener goes to pass-an-ace mode. In particular, 2NT shows 22+.
After X, Opener bids using 1NT systems, including in competition
After GF bids, Opener bids naturally.

After Responder's 1NT

If the opponents are quiet, 2♣ALERT asks for a transfer into a 4 card major. (with minors, 2♠ALERT shows 5♦+4♣, 3♣ shows 5♣+4♦, 2NT shows 5♣+5♦, after which Opener's 3m is NF to play). After 2♦ALERT showing 4 hearts, 2♠ asks for 4 spades and is a 1 round force.

Other bids are natural, 1 round forces. In competition, Opener's X is for takeout. As always, Opener can bid a new suit at the 3 level or cue bid to create a GF.

After Responder's 5-7 suit

A new suit at the 1 or 2 level by Opener shows a minimum with no tolerance for Responder's suit. Opener can also use 2NT lebensohl to sign off. Opener's cue bid, jump new suit, or new suit at the 3 level are all GF.

If the opponents compete, the same general rules apply, but X is for penalty.

Two Level Interference

Pass - nothing to say. 0-7 HCP unless trap passing.
2XALERT - natural, 5+ suit, 4-7 HCP, NF
X - Philip Martin style; 2+ cards in opponent's suit, 3+ cards in all other suits, 5-7 HCP.
2NTALERT - lebensohl, always 5+ HCP
3X - GF (8+ HCP), 5+ suit
3Q - GF (8+ HCP), without clear direction
3NT - 8-11, to play
4m - GF, leaping michaels
4M - 8-11, 7 card suit
4Q - very strong three suiter

Opener's Rebids

If Responder has made a GF call, then Opener can bid naturally and life will hopefully end in a happy game contract.

After Responder Passes

We go to "pass an ace" mode. Opener pretends to pass an ace under the table to Responder and then makes whatever overcall he would've made as if the opponents had preempted. In particular, a 2NT call should show 22-24. If Opener's hand doesn't have much playing strength, this may even imply passing.

After Responder's New Suit at the 2 Level

If Opener has tolerance for the suit in question, Pass and Raise are the main options. With a bad unbalanced hand with no tolerance for Responder's Suit, Opener can bid yet another new suit at the 2 level, or bid 2NTALERT lebensohl. Over this lebensohl, Responder usually bids 3♣ but can rebid their own suit with extra length or a new suit if that looks better. But in any case, a sequence starting with Opener's lebensohl (or 2 level bid) is generally not looking for game, just a suitable place to play.

Alternatively, Opener can bid a new suit or cue the opponent's suit at the 3 level to create a game force. And 3NT is to play, of course.

After Responder's Double

Opener should assume Responder has 5-7 with 3332 negative double shape, and should basically be able to place the contract. If in desperate need of a GF (to make a slam try, for example), 3Q is an artificial GF (if Opps' bid doesn't show that suit, but you want to bid it, start with a penalty pass)

After Responder's lebensohl 2NT

With any minimum, even without tolerance for clubs, Opener should bid 3♣; Responder is presumed to have 5-7 with a good 6 card suit until further notice. Any other bid by Opener is natural and GF.

If Advancer bids at the 3 level over 2NT, Opener's Double asks Responder to bid. At the 4 level, Double is cooperative penalty.

Responder's Rebid after 2NT lebensohl and 3♣ by Opener

Pass - 5-7 HCP, good 6+ club suit prepared to play opposite a bad holding
3X - 5-7 HCP, 6 card suit
3Q - 8-11 balanced with a 4 card major and a stopper
3NT - 12-14 balanced with a stopper

Higher Interference

There is basically not enough room to do anything less than GF bids by Responder. So, X is GF takeout, suit bids are natural and GF. non-leaping michaels also applies over 3 level interference.