Constructed by Jack Marx. Named Byzantine because Byzantium
came after Rome. There is no reason why the ask cannot be a bid other
than 4NT (say 4C).

1. A KEY suit is:-

a] any suit bid and supported.

b] any suit bid by the partner of a NT opener.

2. A HALF-KEY suit is one which is bid but not supported
and not 1b above.

3. Byzantine is not used if there are more than 2 key suits.
(.

4. If there is only one key suit, we permit one half-key suit.

5. Queens only count when accompanied by their kings.

6. Step bid after response asks for other useful cards.

7. Resposes are:-

bid no. of key cards 1 key suit 2 key suits

--- ---------------- ---------- -----------

5C 0 or 3 0 aces 0 aces

3 aces 3 aces

2 aces+key K 2 aces+key king

5D 1 or 4 1 ace 1 ace

4 aces 4 aces

3 aces+key K 3 aces+key K

5H 2 aces or 3 key 2 aces 2 aces

cards AKQ of key suit AKQ of key suit

key AK+half-key K 1 ace+2 key K

5S 4 key cards 2 aces+key KQ 2 aces+key KQ

3 aces+half-key K 2 aces+2 key K

1 ace+key K +key KQ

5NT 5 key cards 3 aces+key KQ 3 aces+key KQ

4 aces+key K 4 aces+key K

3 aces+3 key K

2 aces+key KQ + key K

1 ace + key KQ +key KQ

6C 6 key cards 4 aces+key KQ 4 aces+key KQ

4 aces+half-key KQ 2 aces+key KQ +key KQ

4 aces+key K+half 4 aces+key K+key K

-key K

2 aces+key KQ

+half-key KQ