Opener’s rebids

This is the most challenging position in this bidding system. The previous 1♣ hardly narrows down opener’s hand shape and strength. Hope is not lost, though. The 1♣ opening is just about as nebulous as a takeout double, and the latter has proven its effectiveness in a century of competitive bidding.

After XX

The key feature of XX is to start penalty process. Our further doubles are penalty rather than takeout.

• Pass: content with current contract
• Double: to penalize opposing contract
• Bid a strain at the lowest level: to compete
• Jump to a higher level: strong and distributional

After a transfer to 1M

One step below 1M, including the stolen X, is a transfer to 1M. Bid as if 1♣ - 1M most of the time. However, there are two key differences.

One difference is that opener can bid 1M. Opener now has a way to show 3-card support even when RHO does not compete.

The other difference is that opener gets 2♦♥ cuebids after 1♣ (1♥) X. I’d keep 2♦ as Odwrotka, while 2♥ just asks for stopper. The 1♣ opener is scarcely proud of diamonds. Competition spares this reason to have an artiricial 2♦ reverse.

After the negative double

This is the only 1-level X response not a stolen transfer. It is more urgent to find 4-4 heart fits than transfer to 1NT.

After minor suit transfers over (X)

Only after (X) 1♠, the transfer to diamonds, is opener’s 2♦ natural.

After 1NT or a transfer to 1NT

I suggest keeping 2♦ as an artificial ask like after a transfer to 1M. This 2♦ is the same as 1♣ - 1NT - 2♦.