ASKING FOR ACES CONVENTIONS 

Every partership must have agreements for asking aces and here we will comment about 5 popular conventions used for asking for aces that every advanced player must to know.
1- BLACKWOOD
2- ROMAN KEY CARD BLACKWOOD (RKCB)  - 0314 or 1430 => RKB
3- GERBER - 4 asking for aces after 1nt/2nt opening
4- EXCLUSION RKCB - asking for aces with a void
5- JOSEPHINE 5/5 asking for honors in trump's suit

1- BLACKWOOD is a worldwide standard convention for asking aces invented in 1933 by Easley Blackwood (1903-1992) that is in use until now. This is the conventions that for simplification should be explained in an introductory bridge course but in a more advanced course RKCB => RKB should be introduced.

How Blackwood works?
example1;1
Opener: AK652 K65 K32 A4
Responder: 87 AQJ109 AQ9 KQ6
Opener Responder
 1         2  <= promise 5+ cards
 3*      4nt <= asking for aces (*3 is more strong than 4)
  ?
5 = zero or 4 aces
5 = 1 ace
5 = 2 aces
5 = 3 aces
in continuation Opener bids 5 showing 2 aces according to Blackwood conventions and now having all first control Responder can bid Slam  bidding 6 or may continue asking for kings thinking in 7:
 5         5nt <= asking for kings
 ?
6 = zero or 4 kings
6 = 1 king
6 = 2 kings
6 = 3 kings
in continuation Opener bids 6 showing 3 Kings according to Blackwood conventions, thus Responder having now these informations notify that partnership own 13 tricks and so he bids 7nt:
 6     7nt (having all tricks 7nt is more profit in tournament than 7)

RULE#1 - During the auction if one player jumps to 4nt this is asking for aces unless previos bid was 1nt, 2nt or 3nt, situation where a partnership normally agreed that 4nt in this sequence is a quantitative invitation to 6nt, so in this case, if the bidder of no trump is in the maximum range of his bids, he bids 6nt, else pass.
Exemple1.2 suppose the follow auction:
Opener Overcaller Responder Advancer
  1nt        pass         3nt             4
  4nt  <= this is to play - not asking for aces
Opener Overcaller Responder Advancer
  1nt        pass         3nt             pass
  pass      4            4nt <= this is to play - not asking for aces
 
SHOWING A VOID IN BLACKWOOD RESPONSE
Some partnerships have agreements to show their void during the answer for Blackwood. So, after 4nt the responses are?
- 5nt => useful void and one ace
- jump level 6 shows a void and 2 aces
if the agreed suit is Spades then:
   - jump to 6 shows void in Clubs and 2 others aces;
   - jump to 6 shows void in Diamonds and 2 others aces;
   - jump to 6 shows void in Hearts and 2 ohters aces.
If the agreed suit is Hearts then:
   - jump to 6 shows void in Clubs and 2 others aces;
   - jump to 6 shows void in Diamonds and 2 others aces;
   - jump to 6 shows void in Spades and 2 others aces.
If the agreef suit is Diamonds then:
   - jump to 6 shows void in Clubs and 2 others aces;
   - jump to 6 shows void in Spades or Hearts and 2 others aces;
If the agreed suit is Clubs then:
   - jump to 6 shows void in a indefined suit and 2 others aces.

Note: Playing Roman Keycard Blackwood the convention for void is not the same. In RKC or RKB (Kantar notation) 5nt shows even (0 or 2) keycards and jump to level 6 shows odd (1 or 3) keycards.

example1.3
Opener: AK652 A65 109872 -
Responder: Q4 KQ9 AKQJ9 987
Opener Responder
 1         2
 3         4nt <= asking for aces
  ?
 6 <= 2 aces and void in clubs
              7 <= good bid because where are the Opener honors?
example1.4
Opener: KQ65 A65 - KJ10982
Responder: A5KQJ94 J97 AQ6
Opener Responder
 1         1
 1         2 <= Game Force (GF) 4th suit asking for explanation
 3 <= support 3 cards with a top honor
             4nt <= asking for aces
 5nt <= 1 ace and a void - so Diamonds void
             7 <= easy to bid knowing this void information

example1.5   all Vul
Opener: KQ6542 KQJ10 KQJ -
Responder: AJ1094 - 1054 J9876
Opener Óvercaller Responder Advancer
 1         2             4              pass            
 4nt       pass          5nt(1)        pass   (1) one ace and a void
 6  all pass

THE 4NT OPENING IS BLACKWOOD ASKING FOR ACES
Suppose you have a special hand like:
a) x AKQ x AKQJ1098x
b) KQJ10 AK AKQJ10x 2
c) 5 A KQJ10xxxx AKQ
What is your best open?
For sure is asking for aces bidding 4nt and if opponent interfere partner should use DOUBLE ZERO PASS ONE next suit 2 aces.

Thus Blackwood is a fundamental bridge convention, but Blackwood has weakness in not assuring the possession of important honors like King's trump and Queen's trump that are fundamental  to play a Slam. So Blackwood has been improved by a better convention known as RKCB.
Although you are playing RKCB the 4nt response will still be Blackwood for aces after an opening in suit at level 1, level 2 or level 3.
      Opener           Responder
 1/1/1/1        4nt <= Blackwood despite you are playing RKCB
      Opener           Responder
 2/2/2/2        4nt <= Blackwood despite your are playing RKCB
    Opener           Responder
 3/3/3/3        4nt <= Blackwood despite you are playing RKCB

2- ROMAN KEY CARD BLACKWOOD (RKCB) - RKC0314 or RKC1430 - it is a convention invented in 1960s by the Italian Blue Team - where 4nt asks partner for key cards and there are 5 key cards: 4 aces and the king of trump. The responses for key cards also may shows or denies the possession of trump's Queen.

RKC0314 - asking for key cards after 4nt:
5 = zero or 3 key cards
5 = 1 or 4 key cards
5 = 2 or 5 key cards and denies trump's Queen
5 = 2 or 5 key cards with trump's Queen

RKC1430 - asking for key cards after 4nt:
5 = 1 or 4 key cards
5 = zero or 3 key cards
5 = 2 or 5 key cards and denies trump's Queen
5 = 2 or 5 key cards with trump's Queen
 

INTERFERENCE IN ASKING FOR KEY CARDS AT LEVEL 5 = DOPI:
If opponent bid after our ask for keycards then we use the standard convention Double zero Pass one =>
STEP1 - Double: Shows zero key cards
STEP2 - Pass: Shows 1 key card
STEP3 - next suit: Shows 2 key cards
STEP4 - next+1 suit: 2 key cards with trump's Queen
INTERFERENCE AT LEVEL 6 = DOPE
STEP1 - Double shows odd number of key cards (1 or 3 or 5)
STEP2 - Pass shows even number of key cards (o or 2 or 4)

RKCB was extended by the american world champion 2 times Edwin Bruce Kantar (1932-2022) known as Eddie Kantar in his book "Roman KeyCard Blackwood" that established in its 5th edition a definitive complement for this convention. So using by now his notation:
- Roman KeyCard Blackwood = RKB asks partner for keycards;
- when the agreed trump suit is a major we ask for keycards bidding 4nt;
- when the agreed trump suit is a minor we ask for keycards bidding in jump the agreed minor suit at level 4 (4 or 4);
- when the opening suit is a weak suit (6-10 hcp) bided at level 2 or at level 3 we ask for keycards biddding 4 and ask for aces bidding 4nt;
- after an opening by partner in suit at level 1 Responder bids 4nt to ask for aces (not for keycards).

Read more about KANTAR'S ROMAN KEYCARD BLACKWOO - RKB here

REWIEWING
HOW TO ASK FOR KINGS PLAYING RKB?
There are two most used conventions to ask for the three remainder Kings (King of trump is already known after RKB):

FIRST - Bidding 5nt asking for the number of Kings and the responses are:
6 = zero Kings;
6 = 1 King;
6 = 2 Kings;
6 = 3 Kings.
Experience shows this is not the best information about Kings because in some cases we need to know a specific King that will solidify another suit.
Thus Kantar's orientation is for search specific kings.

SECOND - Bidding 5nt asking for a specific King.
If Spades is the trump's suit then:
6  = shows K and may have other King;
6  = shows K and denies K and may have k;
6  = shows K and denies K, K;
6  = no kings;
6nt = shows 3 kings.

If Hearts is the trump's suit then:
6  = shows K and may have other King;
6  = shows K and denies K and may have K;
6  = denies k and k but may have K;
6nt = shows 3 kings.
To know about K a SSA in 6 will have 2 responses possible:
     6nt <= denie k
     7  <= shows k

From Clubs and Diamonds agreed suit there are no King-ask in 5nt but only in 4nt if the RKB do not use this bid in the keycard-answer.

example2.3 showing the use of King-ask
Opener: AQJ1085 AQJ5 6 A2
Responder: K765K943 AK98 6
Opener Responder
 1         4 <= splinter = singleton/void in Clubs
 4nt <= RKB1430
 .........   5 <= 2 keycards and no Queen
 5nt <= asking for specific King (Asker knows about the Queen)
 .........   6 <= shows K denies k and may have K
 6  <= do you have K?
.........   6nt <= yes I have it but no third control 
.........         with KQ or K second => to bid 7  
 7  <= good we have Grand Slam
             pass <= good luck
 
WHAT RULES DEFINE AGREED SUIT?
 Agreed suit is a suit supported explicitly or implicitly during the auction by Opener-Responder. When there are no room to support partner's suit without sign-off the auction the last suit bidded before 4nt is the agreed suit.
example2.4
Opener Responder
  1        2
  3        4nt <= RKB for  because bidding 4 will be sign-off

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example2.5
Opener Responder
  1       4 <= splinter with implicit 4+ cards support
  4nt  <= RKB1430 for  it is implicit that agreed suit is Spades
example9
 Opener Responder
  1       2nt <= Jacoby-2nt implicit support 4+ cards
  4nt  <= RKB1430 for  because 2nt shows Hearts support

 WHEN THERE ARE NO AGREED SUIT, RKB OR BLACKWOOD?
There are situations in the bidding that Responder is interested only in the number of opener's aces, not in keycards. So we need some rules where 4nt is only for aces or also for keycards.

 Rule#2.1 - When the opening is a weak 6 cards at level 2 or a weak 7 cards at level 3 Responder will use the reserved bid of 4 to ask for keycards in 1430 convention and will use 4nt to ask specifically for aces.
Examples10
Opener Responder (7 KQJ10 AKQJ1076 A)
  2       4nt => Blackwood for aces
   ? <= after Opener response Responder decides:
............... If Opener has 2 aces then 7nt
............... If Oprnrt has 1 ace then 6
............... If Opener hss zero aces then 5

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example2.6
 Opener Responder (5 A AKQJ1096 KQJ10)
  3       4nt => Blackwood for aces
 ............ If Opener has 2 aces then 7nt
............ If Opener has 1 ace then 6
............ If Opener has zero aces then 5

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example2.7
 Opener Responder  (x J10xx AKQ76 AKJ)
  2       4 => RKB1430 for Hearts
............ If Opener has 2 keycards then 6 (6 cards fit)
............ If Opener has 1 Keycard then 5

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example2.8
 Opener Responder (AKx xxxx AKJ AKQ)
  3       4 => RKB1430 for Hearts
............ If Opener has 2 Keycards then 7
............ If Opener has 1 keycard then  6

 Rule#2.2 - After an opening at level 1 in a major a response bid in 4nt ask for aces using Blackwood. Responder has a slammish hand and he is interested only in how many aces Opener has, not in keycards.
Opener Responder
  1         4nt <= Blackwood for aces
Opener Responder
  1         4nt <= Blackwood for aces

 Rule#2.3 - After an opening in a major at level 1 and a response GF at level 2 if the second bid of Opener allows Responder support Opener's suit at level 3, but Responder bids 4nt, then this is a RKB for Responder's suit.
example2.9
Opener Responder (7 KQJx AKQJ1076 A)
  1         2 => GF
  2       4nt => RKB 1430 for (Responder's suit)
.................. Responder has space to support Opener suit at level 3
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example2.10
 Opener Responder (A KQ KQJ10986 KQJ)
  1         2 => GF
  2       4nt => RKB 1430 for (Responder's suit)
.................. Responder has space to support Opener suit at level 3

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example2.11
 Opener Responder  (J107 KQJx AKQ76 x)
  1         2 => GF
  3        4nt => RKB 0314 for Spades (no room for support Spades)

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example2.12
 Opener Responder (K7 KJ10x AKxx KQx)
  1         2 => GF
  3        4nt => RKB 0314 for (no room for support Hearts)

 Rule#2.4 - After a response in two over one GF the 4nt by Opener is Blackwood for aces, not keycard for the Responder's suit.

Opener (AKQJ10xx x KQJ9 x)  Responder
  1   .............................................   2
   ?  <= what Opener should bid to know Responder's aces?
  4nt <= the correct bid for Opener

 Note#2.5: when partnership playing 1430 do not include agreements for situations with no agreed suit some catastrophic bidding may occurs:
exemple2.13
        Opener ........................... Responder            
(KQJxx KQ109x - Qxx)     (Ax x AKQJ10xx AKx)
......... 1 .................................  2
..........2 ................................. 4nt
..........5 ................................. 7nt and Opponent double a hit his ace  
As we see Opener understood 4nt as RKB 1430 for Hearts, but Responder made a Blackwood for aces. Opener and Responder should agreed that this 4nt is a RKC 1430 for Responder's suit (Diamonds).   
HOW KANTAR PROPOSE TO MAKE ASKING FOR KEYCARDS WITH DOUBLE FIT TO HAVE MORE ROOM TO SEARCH IN CONTINUATION:
1- major-major agreement ending in 4 or 4 then 4nt is RKB;
2- minor-major agreement ending in 4 or 4 then 4nt is RKB;
3- Clubs-major agreement ending in 3 or 3 then 4 is RKB
    this strategic allows you to gain 4 steps;
4- Diamonds-major agreement ending in 3 or 3 then 4 is RKB
    this strategic allows you to gain 3 steps;;
4- major-Clubs agreement ending in 4 then 4 is RKB
    this strategic allows you to gain 3 steps;
5- major-Diamonds agreement ending in 4 then the non agreed major is RKB - this strategic allows you to gain 1 or 2 steps.

Thus this summary is very important to understand the way to save space in the responses to RKB when there are agreement in two suits.

Opener Responder
...........   pass
  1        2 <= Qx KQ10zx x A109xx 
 2nt        3 <= singleton (5521)

Opener Responder
...........   pass
  1        2 <= AQ10xx zx KJ10x Jx 
 2nt        3 <= no singleton (5422)

example2.15 When hand fits 
Opener Responder           Opener                            Responder
..........   pass           Kxx Ax AKx A10xxx    AQ10xx x 8x KJxxx 
  1        2 <= Spades and Clubs 9-11 hcp
 2nt  <= ask for distribution    
..........    3 <= singleton (5421)
  4 <= RKB1430 for Clubs
..........    5 <= fifth step -2 keycards and higher Queen (Q)
  7 <= considering 10 cards fit no need to have the Queen
             so we can count 13 tricks    

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example2.16 double fit includes 4A+2K+2Q
So Queens possible = no Q / lower Q / higher Q / both Q
 Opener:  A109x Q109x Ax J98
Responder:  Kx       AKJxx  x   AKxxx
Opener Opponent1 Responder Opponent2  All Vul
  1C        pass           1              3 <= preemptive
  3        pass           4C(1)         pass
  4(2)   pass           4nt(3)       pass
  5nt(4)  pass           6(5)        pass
(1) double suit agreement
(2) weak hand
(3) RKB1430 for
(4) having double fit there are 4A+2K+2Q
     so 4nt is step5 higher Queen Hearts
(5) missing Queen of Club

example2.17
    Operner:  KQ875K8 92 AQ54
Responder:  A75AJ6 K10 KJ1086
Opener  Responder
  1         2
  3         3
  4        4nt (1430/0314 include now one + information)
  ?
  5   => 2 keycards and no Queen
  5   => 2 keycards and lower Queen (Q)
 5nt   => 2 keycards and higher Queens (Q)
  6   => 2 keycards and both Queens
 pass

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 Example2.18
    Operner:  Q87AQ8 AQ982 42
Responder:  AKJ10756 KJ32 AK
If the bidding goes:
Opener Responder
   1        1
  1nt       2 <= nmf
   2        3 <= support for Diamonds suit - forcing
   3 <= cuebid
............. 4nt <= RKB with 6 keycards (Spades and Diamonds)
  6  <= 2 keycards and 2 Queens
              7nt <= 13 tricks counted

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 Example2.19
         Opener:  QJ873 KQJ108 J7 J  nVul
    Overcaller:  64 8 KQ983 KQ942    Vul
     Advancer:  AK5 A6 A1065 A1087
Opener  Overcaller Responder Advancer
   1        2nt*          pass           3
  pass      4             pass          4nt 1430
  pass      6**         pass          7nt all pass
 * minors   ** 2 keycards and 2 Queens
HOW TO SEARCH FOR TRUMP'S QUEEN
 Considering that in RKB the keycard's answer 5 shows 2 aces and trump's Queen and the keycard's answer 5 shows 2 keycards without trump's Queens, when the answer is 5 or 5 the information about trump's Queen is missing so we need a rule for asking for trump's Queen after RKB.

Rule#2.7: After a RKB answer in 5 or 5 the next suit asks for the trump's Queen. If next is the agreed trump's suit then the answer must be made in the next suit+1. Of course the bid of agreed suit is sign-off (to finish the bidding). 

When asking for the trump's Queen responses are:
- bidding agreed trump suit at level 5 denies trump's Q;
- bidding 5nt shows the possession of trump's Queen and denies any of the three remainder kings (King trump already  known);
- having trump's Queen and more kings we must bid the cheapest king possible at level 5 or at level 6.

Supposing trump is Spades () and your answer for RKB was 5 then 5 is asking for trump's Queen. Then responses are:
  - 5 shows Queen and cheapest K may have K-K;
  - 5 (trump's suit) denies possession of the Queen;
  - 5nt shows Queen and denies any other King;
  - 6 shows Queen and k denies K, may have K;
  - 6 shows Queen and K but denies others K;
Supposing trump is Hearts () and your answer for RKB was 5 then 5 is asking for trump's Queen. Then responses are:
  - 5 (trump's suit) denies possession of the Queen;
  - 5 shows Queen and K but may have K and K;
  - 5nt shows Queen but denies possession of others K;
  - 6 shows Queen and K but denies K, may have k;
  - 6 shows Queen and K but denies K and K;

Supposing trump is Spades () and your answer for RKB was 5 then 5 is asking for trumps's Queen. Then responses are:
   - 5 (trump's suit) denies possession of trump's Queen;
   - 5nt shows Queen but denies others Kings;
   - 6 shows Queen and K, may have K and K;
   - 6 shows Q and k, denies K, may have K;
   - 6 shows Queen and K, but denies k and K;
Supposing trump is Hearts () and your answer for RKB was 5 so 5 is asking for Queen. Then responses are:
  - 5nt shows Queen but denies possession of other K;
  - 6 shows Queen and K, may have k and K;
  - 6 shows Queen and K but denies k, may have K;
  - 6 (trump's suit) denies possession of trump's Queen;
  - 6 shows possession of Queen and K - denies K and K;
example2.20 using RKB 1430 Opener is the strong hand
 Opener Resp   Opener    Resp    explanation:             
  1        2       AKJ954 Q83   (0) 16+ hcp
  2nt(0) 3(1)   AQJ4     K        (1) more strong than 4
  4nt(2) 5(3)  4          AQJ84 (2) RKB for
  5(4)  5(5)  A           K82    (3) 1 keycard
            (4) asking for the trump's Q
            (5) I have Q and K
  7      pass

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 example2.21 using 0314 Opener jumps so he is the strong hand
Opener Resp     Opener    Resp    explanation:             
  1        1         AQJ10  K983  (1) 1 keycard  
  3        4nt       Q4        A43    (2) asking for Q
  5(1)   5(2)   54         AK84  (3) I have Q + K  
   6(3)   7        KQJ109 A2   

----------------------------------------------------
example2.22 using 0314 Opener jumps he is the strong hand
Opener Resp    Opener Resp    explanation               
  1         1        A8       K983 (1) zero/3 keycards
  4         4nt      KQ94   AJ43  (2) asking for Q trump
   5(1)    5(2)  54        A84   (3) I have Q and K
  6(3)    7       AKJ85  Q2

 -----------------------------------------------------
 example2.23 using RKB 0314 Opener jumps he is strong hand
Opener Responder Openr Responder   explanation              
  1         1           AJ9    KQ832  (1) fit in  
  2nt       3(1)     KJ10   A4         (2) to play             
  3nt(2)  4(3)     K764  AJ98      (3) RKB for  
  5(4)   5(5)     AQJ    K2          (4) 3 keycards
  6(6)   pass      .....................        (5) asking for Queen
................................................        (6) no Trump's Queen

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 example2.24 using RKB 1430 Responder is the strong hand
Opener Resp     Opener Resp   explanation               
  1         2        AQJ53  97      (1) 1 keycards  
  3        4nt       J           AQ93  (2) asking for Q
   5(1)    5(2)  QJ9      A10     (3) I have Q but no Kings
 5nt(3)   6       QJ102   AK843 
 pass 

-------------------------------------------------------
example2.25 using RKB 0314 Opener reverse
Opener Responder Opener Responder explanation            
  1         2          AQJ105  6              (1) 16+ hcp
  3(1)    3          J7           AK10983 (2) RKB 0314
   4         4nt(2)   K9           A87         (3) 1 keycard
  5(3)    5(4)     KQJ9       A32         (4) do you have Q?      
  6(5)    pass  .................................      (5) no trump's Q        

HOW DOES RKB WORKS AFTER SPLINTER?
Considerations: Remember that a Splinter is a invitation for Slam with a limited strenght up to 17 points with 4 cards support and a singleton (3 points) or in rare ocasions a void (5 points). It is a situation where both players have a significative strength to try game and if the splinter's hand fits with the Opener hand there are also possibility of a Slam or even Grand Slam.
Any partnership need use a mechanism to show their controls (Aces and Kings) and the most use is after the splinter do a cuebid. When a player cuebid in a suit he shows a control in a suit and may also denies a control in other suit.
Kantar in his reference bood about KEYCARDS create another way to show the controls. After the splinter his orientation with minimum opening hand or when the splinter does not fits Opener should sign-off bidding the agreed suit.
A hand fits when the singleton suit have 3 losers in the other hand:
 xxx - x or Axx - x
A hand does not fit when the singleton have top honor in the other hand:
 KQx - x or AKx - x

In case Opener have a good hand and splinter fits then there two ways to continue:
 a) take charge and ask for RKCB1430 bidding 4nt
 b) having space Opener explain his hand to partner as a response for RKB.
     b1 - in the 4th edition of his book Kantar propose 3 possible responses for Opener explain his hand:
      1st  step - 2 keycards with Queen (not ace cuebid);
      2nd step - 3 keycards without Queen (not ace cuebid)
      3rd step - 3 keycards with Queen (not ace cuebid),
            then partner may sign-off or try Slam.
     b2 - in the 5th and last edition Kantar propose 4 possible responses to Opener explain his hand:
      1st  step - 2 aces + 1 king (any) + trump's Queen;
      2nd step - 3 aces + 1 king (any);
      3rd step - 3 aces + 1 king (any) + trump's Queen;
      4th step - 4 keycards
            then partner may sign-off or try Slam

Thus a regular partnership must select a mechanism to use after splinter. Following Kant we suggest the mechanism of 4 steps proposed in Kantar's  last edition.
     
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example2.31
 Opener Resp    Opener Resp            explanation               
  1nt      2(1)    AQ     KJ10xxx  (1) transfer
  2       4(2)    10xx   3             (2) splinter and 6+ cards
   4nt      5(3)   KQxx   Axx         (3) zero or 3 keycards
  6       pass     KQxx   Axx
 Note: if Responder has only 6 cards and only one more ace then he will make a sign-off transfer at level 3, so this splinter is an invitation for possible Slam.

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example2.32
 Opener Resp    Opener Resp            explanation               
  1nt      2(1)    Axx     KQJ10xx  (1) transfer
  2       4(2)    Kxxx   Axx          (2) splinter and 6 cards
   5(3)  6         Axx     x              (3) second step 3 keycards
  pass                A10x   KJx                 without Queen
besides was 1nt with 15 hcp the splinter fits the hand

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 example2.33
 Opener Resp    Opener Resp            explanation               
  1nt      2(1)   KQJx   KJ10xxx (1) transfer
  2       3(2)   Jx        AQxxxx  (2) splinter in spades with 6
   3nt(3) pass    AQxx   Kxx         (3) strong spades stoppers
 ....................    Kxx     Axx

 ------------------------------------------------------------ 
example2.34
 Opener Resp    Opener Resp            explanation               
  1nt      2(1)   Jx      AKxxxx    (1) transfer
  2       4(2)  KQJx   3              (2) splinter and 6 cards
   4       pass    AQxx  K84         
                        QJx     Kxx

 --------------------------------------------------------- 
example2.35
 Opener Resp    Opener Resp            explanation               
  1nt      2(1)    Kxx     Ax           (1) transfer
  2       4(2)    Kx       AQJxxxx   (2) splinter and 6 cards
   4nt(3) 5(3)   AKxxx x              (3) take charge - RKCB
  6       pass      Kxx     Qxxx       (4) 2 keycards with Queen
 Note#5: the opener's hand is compose by Ace and Kings that are the principals controls for make tricks and the AKxxx - x have 62% in a 4-3 division big chance to find 3 tricks here.

--------------------------------------------------------------
 example2.36
 Opener Resp    Opener  Resp            explanation               
  1       4(1)  AJ98xx Kxxx   (1) splinter
  4(2)  4(3)  QJ10    Kxxx   (2) 2 keycard with Queen =10 cards
   pass               Axx      x         (3) sign-off missing 2 keycards
                        x           KQJx      
Note#6: the splinter fits but misses 2 keycards
Opener Responder               Opener                          Responder
   1D       2D <= 10+ hcp   AQJxKJ109xAQ10x   KxKQJAxxxJ9xx
  4D   <= RKB1430
             4 <= 1 or 4 keycards (assume 1)
  4   <= partner do you have trump's Queen
  .......... 5D  <= no I don't have it
 pass <= missing 2 keycard and trump's Queen

Note: Apparently the chances for Slam are not good since a significative incertainty exist in the Clubs suit due to the precipitate bidding made by the Opener in not bid a splinter in 3 that may correct the contract to 3nt.    

===========MORE EXAMPLES FOR RKB ================

---------------------------------------------------------------
example2.46 missing additional Kings - information given by Queen-ask
Opener Responder                 Opener                        Responder
  1C       2C                    AxAxxAQxK10xxx   QJxQxxxxAQJ9xx
  4C       4D <= 1 or 4 keycards (assume 1)
  4  <= partner do you have trump's Queen
  .......... 4nt <= yes I have it but no Kings
  5C  <= no Kings, so let's stop the bidding now
  .......... pass

--------------------------------------------------------------------
example2.47 missing additional Kings - information given by Queen-ask
Opener Responder               Opener                            Responder
   1D       2D <= 10+ hcp   AxxAxxAxxxAQ10  QJxQJxKQJ10xxJ
  4D  <= RKB1430
             4 <= 1 or 4 keycards (assume 1)
  4  <= partner do you have trump's Queen
  .......... 4nt <= yes I have it but no Kings
  5D  <= no  Kings, so let's stop the bidding now
 ...........  pass

------------------------------------------------------
example2.48 response for specific King is 6nt when there are 3 Kings
Opener Responder               Opener                       Responder
   1       1                  Kx Kxx Kxx Axxxx  Axxx Ax Ax KQ109x
  1nt      2  <= nmf preparing to establish game force
  2nt      <= denies 4cards and 3 cards
  .......... 3  <= GF with Clybs agreed suit
  3nt <= stopper in all unbid suits
  .........  4  <= RKB1430 try for Slam
  4  <= 1 keycard
  .......... 4nt <= Asking for Specific King
  6nt <= 3 kings
 ...........  7  <= Kx in Spades because nmf deny support so 13 tricks

---------------------------------------------------------------
example2.49 after RKB we Ask for Specific King with 4nt
Opener Responder                 Opener                           Responder
  1       2                Ax AKJ10 AK109xx x   KJxxx xxx AJx xx
  2       3 <= playing Leb after reverse this is GF
  4  <= RKB1430 in Clubs
  .......... 4 <= show 1 keycard
  4nt  <= Asking for King do not promise all keycards it is a try for Slam
             5 <= shows King Spades denies K and K
  6   <= even missing one keycard it is a satisfactory try considering 6 cards .

Note: after the reverse bid Responder without any King, lets say with Qxxxx having 7 hcp should inform Opener about the strength of his hand bidding 2nt transfer to Clubs and then supporting Opener in Diamonds. Of course Opener with his strong hand will bid game in 5.

----------------------------------------------------------------
example2.50 after RKB and after SKA we search control in a suit with SSA
Opener Responder                     Opener                    Responder
   1       2D <= 10+ hcp   xxAKJ10xJ109xKx   AxQx AKQxxxAxx
  3D  <= 4 cards support ................... Specific Suit Ask (SSA) responses:   
             4D <= RKB1430 ....................   first step => Qxx
  4  <= 1 keycard .............................   second step => Kxx
             4nt <= Specific King Ask ......   third step => Kx or KQx
  5  <= Shows K .............................   jump to agreed suit => singleton
 ...........  5 <= SSA do you have K ..   return to agreed suit => nothing  
  5nt <= second step so AKxxx
 ...........  7 I can count 13 tricks with Opener having 9 red cards
 pass

 ------------------------------------------------------
example2.51 another SSA after SKA
 Opener Responder                 Opener                            Responder
  1C       2C                        xx AKJ10x J109x Kx   Ax Qx AKQxxx Axx
  4C  <= RKB1430
  .......... 4 <= 2 keycards whitout Queen
  4nt <= Specifi King Ask
  .......... 5 <= shows K and denies KD
  5  <= SSA - partner what you have in Spades
  .......... 5nt <= third control (Qxx or Qx or xx)
  6C  <= let's stop in 6C
  ..........  pass

After a Specific King Ask a second King Ask have the follow responses:
- first      step => including 6nt shows Kxx(x)
- second step => Kx
- third    step => raise the ask-suit to show KQx
Without the King of the ask-suit Responder returns to the agreed suit

----------------------------------------------------
example2.52 Search for another King after SKA
Opener Responder                    Opener                         Responder
   1D       2D <= 10+ hcp      AK AJxx AQxxx xx   xx KQx Kxxxx AKx
  4D  <= RKB1430
  .......... 4 <= 2 keycards whitout Queen
  4nt  <= Specific King Ask
  .......... 5 <= K and may have other King
  5  <= partner do you have the K?
 ........... 6 <= third step = KQ
 7nt  <= I can count 13 tricks
...........  pass

================ end of RKB =============
3- GERBER - it is an important convention introduced by John Gerber in 1938 (already published in Europe -1936) where after an opening in 1nt or 2nt or a jump to 2nt, Responder asks partner to show the number of aces held bidding 4 using the follows responses:
   4 = zero or 4 aces / 4=1 ace / 4=2 aces / 4nt=3 aces
and in continuation 5 will ask for kings, but here we will not use Gerber for Kings because here we will use that any suit bidded at level 5 by the asker is sign-off to allows asker play in that minor suit when asker has zero or 1 ace but long and solid minor suit.

---------------------------------------------------------------
MODERN USE OF GERBER BY KANTAR
In Kantar's book "Roman Keycard Blackwood", that is the best reference for asking aces, kings and also Queens, Kantar uses two conventions for Gerber:
1- simple or traditional Gerber to be used after 1nt or 2nt opening;
Opener Responder
   1nt      4 <= simple Gerber (asking for aces: 4=0 4=1 4=2 4nt=3)
 Opener Responder
   2nt      4 <= simple Gerber (asking for aces: 4=4 4=1 4=2 4nt=3)

2- RKB Gerber that changes the 4 steps of Gerber to steps of the RKB1430 and to be used after the follows sequences:
Opener Opponent Responder Opponent
  1         pass        1/1/1     pass
  1nt       pass           4 <= RKB Gerber in Responder's suit
 Opener Opponent Responder Opponent
  1         pass          1/1         pass
  1nt       pass            4 <= RKB Gerber in Responder's suit
 Opener Opponent Responder Opponent
  1         pass            1            pass
  1nt       pass            4 <= RKB Gerber in Spades
 Opener Opponent Responder Opponent
  1         pass        1/1/1     pass
  2nt       pass           4 <= RKB Gerber in Responder's suit
 Opener Opponent Responder Opponent
  1         pass          1/1         pass
  2nt       pass            4 <= RKB Gerber in Responder's suit
 Opener Opponent Responder Opponent
  1         pass            1            pass
  2nt       pass            4 <= RKB Gerber in Spades
----------------------------------------------------------------------------

WHY IS GERBER SO IMPORTANT?
Answer: because when we want to play game in a minor with good hand but without aces if we bid 4nt asking for aces and there are 2 aces missing, we have to stop the bidding at 5nt and with more probability in lose the contract that is very good for playing in suit like in this situation:
you have: KQJ8 x x KJ98732
partner has: A32 KQJ Q9x AQ64
the bidding goes:
example3.1
Opener   Responder (you)
 1           1
2nt           ?
if you bid 4nt asking for aces and partner's response is 5 or 5 you have a great problem, but if you bid 4 Gerber and partner's response is 4 (2 aces not keycard) then you bid 5 and partner obeys and passes, but if partner after Gerber 4 bids 4nt (3 aces) then you bid 6 sure to make and more, if partner after Gerber 4 bids 4 (zero or 4 aces) you assume 4 aces and should bid 7 to make.    

Similar situation occurs when you have:
 8 x KQJ109xx KQ109
and partner opens 1nt or 2nt. Bidding 4 Gerber, also known 4 Blackwood, you have at level 4 the information for your final contract in 5 or 6 or 7.

Lets show some sequences where Gerber could be applyed using now the modern Gerber proposed by Kantar.
First remember that after a 1nt opening 4nt is no more asking for aces:
Opener Responder
  1nt       4nt <= quantitative
Quantitative means: If Opener have 17 hcp or good 16 hcp with 5 card suit then he bids 6nt, otherwise passes.
This information if 1nt is 15 hcp or bad 16 hcp versus 17 hcp or good 16 hcp is so crucial that experts like Eddie Kantar considers more important to know maximum or minimum than the information of trump`s Queen or about a specific King when one hand is 1nt balanced.

-------------------------------------------------------
exmple3.2
a) after 1nt open:
Opener Responder
  1nt       4 <= Gerber - asking for aces (not for keycards)

----------------------------------------------------------
example3.3
 Opener Responder
   1nt       2 <= Stayman
 2/2     4 <= RKB 0314 Gerber - asking for keycards (*) (not splinter)

--------------------------------------------------------
example3.4
Opener Responder
   1nt       2 <= Stayman
 2/2    4nt <= quantitative (**) (not asking for keycards)

Note#7: in * or ** most bridge players in these sequences will understand 4 as splinter and 4nt as RKB0314, so you only can play that after have made agreement with your partner. We recommend the use of the popular way, splinter and RKB0314, but up to you.

-------------------------------------------------------
example3.5
b) after 2nt open:
Opener Responder
   2nt      4 <= simple Gerber - asking for aces
and after Opener shows 4

-------------------------------------------------------
example3.6
Opener Responder
   2nt       3 < Stayman/Puppet
 3/3    4 < RKB0314  - asking for keycards

-----------------------------------------------------
example3.7
Opener Responder
   2nt       3 < Stayman/Puppet
 3/3    4nt <= quantitative

Note#8: again this is only for expert's partnership who has already discussed these sequences and knows their advantages.

---------------------------------------------------
example3.8
c) after reverse in 2nt showing 18-19 hcp
Opener Response
1suit     1suit
2nt        4 <= RKB0314 in Responder suit

----------------------------------------------------------
example3.9
Opener Responder
   2nt       3 < Stayman/Puppet
 2/2    4nt < quantitative

-------------------------------------------------------------
example3.10
d) playing inverted minors after:
Opener Responder with no interference
1          2
4 <= is RKB1430 Gerber asking for keycards in Clubs

--------------------------------------------------------------
example3.11
Opener Responder
1         2
4 <= is RKB1430 Gerber asking for keycards in Diamonds

--------------------------------------------------------------
example3.12
Opener Responder with no interference
1         2
2suit     4 <= is RKB1430 Gerber asking for keycards in Clubs

----------------------------------------------------------------
example3.13
Opener Responder
1         2
2suit     4 <= is RKB1430 Gerber asking for keycards in Diamonds

Conclusion: we are using Kantar's recommendation about Gerber but for using these conventions you need to have long agreements with your partner.
Thus be careful in using it when you are playing with a new partner and had no time to discuss these specifics conventions that needs agreements by partnership.
When you have a regular partner you need make agreements to decide about the use of 4 Gerber asking for keycard and 4nt quantitative or to use 4 splinter and 4nt 1430.
When you use 4nt quantitative and 4 Gerber playing Bergen raises the responses more common are:
- the splinter GF 12-14 hcp is bided in jump to the other major at level 3 and Opener search for the singleton bidding next suit:
Opener Responder
  1         3  <= artificial bid showing 4+ cards 12-14+ hcp
  3nt <= ask for the singleton
               ?
              4 <= Clubs singleton
              4 <= Diamonds singleton
              4 <= Spades singleton
Opener Responder
  1        3  <= artificial bid showing 4+ cards 12-14+ hcp
  3  <= ask for the singleton
               ?
             3nt <= Clubs singleton
              4 <= Diamonds singleton
              4 <= Hearts singleton

The others response bids at level 3 are change in position and 3c > 3d:
Opener Responder
  1        3  <= 4   cards and 2-6 hcp
  1        3  <= 4   cards and 2-6 hcp
  1        4  <= 5+ cards and 2-6 hcp
  1        4  <= 5+ cards and 2-8 hcp
  1        3  <= 4   cards and 10-11 hcp
  1        3  <= 4   cards and 10-11 hcp
  1        3  <= 4   cards and 7-9 hcp
  1        3  <= 4   cards and 7-9 hcp

The responses bids at level 4 are:
Opener Responder
  1       4   <= RKB1430 for Spades
  1       4   <= RKB1430 for Hearts
  1       4   <= transfer to the other major up to 10 hcp 7/8 cards
  1       4   <= transfer to the other major up to 10 hcp 7/8 cards
  1       4   <= transfer to Spades with 18-19 hcp balanced with 3 cards
  1       4   <= transfer to Herats with 18-19 hcp balanced with 3 cards
  1       4   <= 5+ cards and 2-6 hcp
  1       4   <= 5+ cards and 2-8 hcp
            
       
4- EXCLUSION RKB
 When Responder has a void and strong support in the Opener suit, or when Opener has a void and strong support in Responder suit, then a jump in level 5 in the void asks for KEYCARDS in last bid suit with the exclusion of the ace of the suit bid at level 5.

The answers for RKB1430 are:
1o. step = 1 or 4;
2o. step = 0 or 3;
3o. step = 2 keycards without trump's Queen;
4o. step = 2 keycards with the trump's Queen.
after the answer if partner bids the cheapest suit this is Grand Slam try asking for the trump's Queen. So without the trump's Queen the teller (Responder) bids the agreed suit else having it the teller jumps to seven of the agreed suit.
After the answer if partner bids the agreed suit in any lev el this is conclusive (sign-off).
example4.1
Opener Resp      Opener   Resp      explanation         
  1          5(1)  A1093   KQ32   (1) exclusion in 
   5nt(2)   7        A874     93       (2) 2 Keycards no Q    
  pass ................ K9          -          
  .......................  72         AKQJ843  

---------------------------------------------------------
example4.2
Opener  Resp    Opener Resp explanation
  1         5(1)  A1093   K3  (1) exclusion for 
  6(2)    7       Q874      -    (2) 2 Keycards with Q
  pass .............  A6         KQJ6      
  .....................  Q82       AKJ10843 

----------------------------------------------------------
example4.3
 O: AKQ9  - D KJ10xxxx C Kx
R: xxx  QJx-D Axxx C A85
Opener opp1 Responder opp2
 1D        pass     2D            2nt
 5*    double   5**       pass
 7D      all pass
* exclusion RKB (void in )
**step3 =2 keycards no QD
with 11 trumps no need Q

------------------------------------------------------------
 example4.4
O: AKQ943  AKQxx D - C Kx
R: Jxxx  x DA1098x C A85
Opener opp1 Responder opp2
 2C        pass     2D            pass
 2        pass     3            pass
 5D*      pass     5**        pass
 7       all pass
*exclusion - AD not count  
** first step = 1 keycard (ace Diamonds is exclude)

EKB - Exclusion RKB for minors
Kantar in his book "Roman Keycard Blackwood" has a optional chapter for Exclusion RKB for minors. Kantar use the notation EKB for RKC1430 with a void after minor-suit agreement.

To avoid ambiguity with splinter the EKB occurs in a superior jump level of the splinter. So after an agreement at level 2 Opener having singleton in a major will splinter bidding his singleton at level 3, but if Opener have a void in a major, and of course a strong, he will ask for keycards bidding EKB1430 at level 4 like:
example4.5
Opener Responder       Opener                              Responder
  1C        2C             - KQx DKQJx CAJxxxx    Jxx Ax DA10x CKxxxx
  4 <= EKB1430 in Spades
  .......... 5C <= second step shows 3 keycard
  now Operner may ask for Queen bidding 5D but with 10-11 cards fit it is not necessary, so Opener bids Grand Slam.
  7C      pass

Note: For Responder it is more rare the use of EKB at level 4 and so EKB need be use at level 5. Responder need first establish the agrred suit and after use the RKB. A directly jump to another suit at level 4 need a convention with partner and may be to play or to transfer to the strong hand, so it is not a EKB

5- JOSEPHINE CULBERTSON CONVENTIONS - Wife of Ely Culbertson was an expert bridge player and in 1936 she wrote an article in Bridge Word about her husband's convention to search top honors in agreed trump suit. This convention was changed and became popularized only for majors suits (not really the original article), but useful in many situations.

1-When we want to know the top honors (A/K/Q) in a agreed major suit, we jump to 5 of this suit and the answers are:
- pass = zero or 1 top honor (A/K/Q);
- 6 in the agreed suit = means 2 top honors (AK/AQ/KQ)
- 7 in the agreed suit = means 3 top honors (AKQ)

example5.1
 Opener  Resp    Opener Resp      explanation               
  1         5(1)  K9732 J865      (1) Josephine
 pass(2) ......     AK4     -             (2) 0 or 1 top honor
 ...................     75       AKQJ65  5 is the final bid and
....................     Q82     AK          contract could down 1.
-------------------------------------------------------------

 example5.2
 Opener Resp      Opener  Respr     explanation            
  1         1......  AKQ3    108652 (1) splinter - 4 cards
  4(1)    4(2)   KQJ876  -           (2) waiting for cuebid
   4(3)    5(4)   52         AKQJ5  (3) no A good news
  7        all pass  7          A8         (4) Josephine

JOSEPHINE 5NT 
 When we have all controls and the question is Slam or Grand Slam, then we want to know if partner has 2 top honors in agreed trump suit and we make a GRAND SLAM FORCE jumping to 5nt, bypassing the 4nt bid, and partner must bid 6 or 7 in the agreed suit depending on 1 or 2 top honors in trump suit.
example5.3
 Opener Resp    Opener Resp explanation   
 1        2        KJ932  -              (1) Fast Arrive weak
  4(1)  5nt(2    AK4    QJ976532 (2) Grand Slam Force
 7(3)  ..........  75       AK4           (3) I have 2 top honors 
.....................    Q82    AK           we only need top honors

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