SIGNALING FOR COUNT, ATTITUDE AND SUIT PREFERENCE 

a)       dummy             Q93       West            East  AK82         107         declarer             J654

b)    dummy             983   West              East AK52          Q107         declarer           J64

c)        dummy            QJ432     West             East  AK65           1087           declarer               9

In (a) West leads A and East serves the 10 to show interest in ruffing the third round of Spades.
So after the K East serves the 7 showing his doubleton.
In the third round of Spades West may suggest the return in Hearts or in Clubs depending on if he plays a high spot card (8) or a low spot card (2) West will make an indication of his suit-preference giving the ruff.
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In (b) West leads the A and East serves the 10 to show interest in this suit continuation because he has the Queen that may win the third round in Spades. West doesn't know if this is a signal for dubleton or for Queen, he just obey partner's signal for continuation in this suit.
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In (c) West leads A, East serves the 7, Declarer serves the 9. Now West looks at his cards and dummy cards to conclude that low seven is third (or singleton). In this case he must consider shifting to other suit but if he doesn't see other any way to defeat (unless making 3 tricks in Spades) he may continue in this suit despites the low probability of success.

Note: The lead of Ace without King is not recommended and so when done it is a desperate attempt to find where partnership can make tricks.

Attiude Signal in defense against their NT contract

In fact Attitude Signals are a priority signal over the Count Signal mainly when defending against their NT contract.

Let's suppose that opponents are playing 3nt and partner leads K, so he may probably have KQ10xx. If you play STD and have A85 or J85 in this suit you should not make a count signal but should make an attitude signal informing partner that you have an honour playing a high card like your 8 or a low card in case you have no honor. But for this specific lead you should serve A or J because the 8 isn't a clear signalization of honor for your partner you could have only 98, so this lead demands the play of your top card in this suit.

In case you are those economical players with high cards and just play an attitude signal with 8 there is a risk that partner having KQ10xx shift to another suit supposing Declarer with AJx. Of course if you has Ax or Jx you have no choise than play your high honor. 

When this lead is made with only 4 cards KQ10x if Declarer has A97x or J97x the economical player having A85 may work making just an attitude signal with his 8. These crucial decisions must be supported by the bidding to count declarer's possible distribution or by dummy cards. But leads with K in 4 card suit like KQ10x are not recommended because leading with K if partner has Ax or Jx may produce a trick for declarer.

Curiously many players with KQ10x(x) use to lead with Q to show the possession of the 10 and having KQ98(x) leads the K to denies the 10 but showing the possession of the 98. You can ask opponent about their convention against NT, when lead is K, before you make your decision. 

When the Leader has KQJ9 and leads the K against NT, dummy shows xxx, if partner with A82 just make an attitude signal with the 8 the Leader must continue with the jack to show 4+ cards because the continuation with the Q shows only 3 cards and partner will understand that declarer has J10xx and to avoid to kill the Q with his ace will play low supposing that his partner leads for 4 cards in his hand.

Note: Considering that Attitude is the priority signal when partner leads Responder must signal first Attitude and only after count. So Responder in his second discard (in this suit) must signal showing his present count (if he was 5 cards and now has only 4 his present count is 4) playing a high card if he is now even or playing a low card if he is now odd.

In suit contract Count is very important to give ruff

Let's see this interesting example in defense against a contract of 3

	A3  J2  86542  AK83		bidding:   S     W    N      E pass  1 pass  3* all pass        *10-11 hcp        lead A After North leads the A South must serve first the 9 to show doubleton. Declarer serves the 10 (false card) trying to stop Clubs continuation, but North knowing possible false card continues with the K and South serves the 2 with Declarer serving the 7.
Q85  AK654  A6  1076	N W      E      S	KJ3  10743  K9  QJ54
	109873  Q2  QJ10  92

Then your North plays the 8 and dummy serves the J and South ruffs with the 2 with Declarer serving the 6.
Now South have to play and he notice that the 3 is missing. If North has the 3 why he plays the 8?
The convention for suit-preference when giving a ruff to partner is to play a high card to receive return in the higher ranking suit (excluding trump and the current suit) and play low card to receive return in the lower ranking suit. So North asks to South a return in Spades.
Then South plays the 3 and North makes his A to play Clubs again. South ruffs the Q with Q and when Declarer overruffes with his K this upgrades partner's J2 to be a trick and contract down 1!

Playing STD and showing suit-preference to other suit:

	AKQ84  872  J43  J3		bidding:   W    N     E     S                 1   1   2    2                 3   all  pass  Lead: A         After North makes AK notify that partner gives in first trick the count playing 2 and then in trick2 serves the 10 to show a clear suit-preference to Diamonds. So North plays J to defeat the contract because now N-S makes 3 tricks in for down 1. In case South serves 6 North shifts to Clubs.
975  AKJ65  653  AQ	N W      E      S	J3  Q104  K982  K982
	1062  95  AQ10  107654

	AKQ84  872  J43  J3		bidding:   W    N    E      S                 1   1   2   all pass Lead: A         After North makes AK South discards 2 in the third round of Spades, in STD this means South denies preference for Clubs and by exclusion North shifts to Diamonds playing J to defeat the contract because now N-S makes 3 tricks in Spades and 3 tricks in Diamonds. Without a convention signal North may guess wrong shifting to Clubs
975  AKJ65  653  AQ	N W      E      S	J32  Q104  K982  K982
	106  95  AQ10  107654

What are the most recommended leads playing STD?

Basiclly STD leads are made in the 4th higher card:
with K10532 the 4th card here is the "3";
with K1032 the 4th card is the "2";
with K104 the lead is the 3th card here the "4".
But when we have no honor in the suit the lead is made in second higher:
with 97632 the lead is the "7"
with 8653 the lead is the "6"
with 862 it is better not lead in this suit
When there are sequence then lead is made in the top of sequence:
with J109xx the lead is the "J"
with 98762 the lead is the "9"
with QJ32 the lead is the "2"
with QJ432 the lead is the "3"
with QJ92 the lead may be Q or 2 depending on what bidding showed
with QJ932 the lead may be Q or 3 depending on the bidding
with QJ10x(x) the lead is Q
with KQ32 the lead is "2"
with KQ432 the lead is "3"
Specials leads against NT not  only specific to STD leads:
with KQ10xx the lead is the "K" (promising Q10)
with AKJ10 or AKJxx the lead is the "A" (promising KJ)
Journalist leads against NT: the 10 promisses honor and jack denies
with J108xx the lead is the "J"
with KJ10xx the lead is the "10"
with A109xx the lead is the "10"
with AQ1053 the lead is the "5"
with AQ1093 the lead is the "10"
with AQ109x the lead could also be the Q supposing Jx in dummy
with AK1053 the lead is the "5"
with AK1093 the lead is the "10"

Ace for attitude, king for count
There are some partnership that having Ace and King (AK) sometimes leads the A and sometimes the K. They lead the Ace asking for attitude signal and they lead the King asking for count.

Leading against NT contract when the leader has 5+ cards (AKJxx) he tries to avoid giving a Queen second. So if dummy has 3 low cards and partner shows odd length then Queen is second. The same apply if partner has 4 cards like 9653 and dummy and Declarer have also 2 cards. Now serving the "9" this could be interpreted as 4 cards in STD.
 
But this may be good when Declarer opening shows strong hand and you have to defend against 3nt having only AKJxx supposing partner has blank hand.

To avoid ambigous information for a normal defense against NT Ace's leads shows AKJxx asking also for count or for the discard of the Queen.

King's leads denies Ace and shows KQ10xx (or KQJxx) asking for partner discard the jack or cover with the ace.

Playing against suit contract King's lead is not so ambiguous specially when the leader opens 2 weak or in a major and was supported by partner. In this case the lead of King may be also interpreted as asking for Count and also give oportunit to discovery where partner may have honors. So in some specific situations attitude is not more the relevant information so first priority is count then suit-preference. 
 
Having a new partner you should ask his opinion about these leads.

Leading with the King having AK second
Against suit contract in some ocasions we lead the King and after play the Ace to show dubleton and to ask partner a indication of his entry. We want to ruff in 3rd round of this suit. So after playing Ace partner plays low or high as an indication of entry excluding current suit and trump suit.

So if the contract is 4 and you leads K partner first signals should be attitude and having J32 9542 A982 92 he plays 2 but after you play the A partner understanding that you have AK second plays the 9 to show his entry in Diamonds.

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UPSIDE DOWN COUNT ATTITUDE (UDCA) system discard

This method of signals is reverse to STD. So when Declarer is playing a suit if you have 3 cards (863) you play first the middle card (6) and after the low card (3) to show odd; if you have 2 cards (94) or 4 cards (7652) you play the low card first to show even; and in case you have 5 cards then you play first the second low card 97432 here the "3" and after the low "2". For sure partner will know how many cards you have in this suit.
 
As ATTITUDE you play low to encourage the continuation and play high to discourage the continuation. Of course partner must look for all cards in this suit to know, for example, if a 7 is a low or high.

Using UDCA the leads are normally made in the 3rd higher with 4 cards and in 5th card higher with 5 cards. So with K10532 you lead the "2" and with K1052 you lead the "5".

Be careful, when opponents are showing suit-preference. Some UDCA partnership discard low asking for the higher ranking suit and discard high asking for lower ranking suit. So they may invert all - you don't lose anything in asking for their method of suit-preference.

Examples from the use of Attitude Signals with UDCA:

a)       dummy             Q93       West            East  AK82         107         declarer             J654

b)    dummy             983   West              East AK52          Q107         declarer           J64

c)        dummy            QJ432     West             East  AK65           1087           declarer               9

In (a) West leads A and East serves 7 to show his dubleton. Declarer plays 5 (false card); West suppose now that East may have 3 cards so the continuation in this suit may release a winer Q and then West may shift to another suit. In case West didn't have other option he continues with K and when East serves the 10 he knows partner has doubleton. Then West continues Clubs giving partner's ruff and also playing a suit-preference card for East return. 

In (b) West leads A and East serves the 7 his low card to show interest in continuation. Declarer serves the 6 (false card). West didn't see the 4 so he supposes partner may have J74 and stops the continuation shifting to another suit. Of course if partner has QJ7 he should play the Queen to show his Jack and then West plays low Club because QJ also may be doubleton. 

In (c) West leads A and East plays the 8 and Declarer the 9. Now West looking for his cards and dummy cards to conclude that 8 may be 3 cards, or doubleton or singleton. In this case he must change for another suit but if he didn't see another way to defeat unless making 3 tricks in Spades he may continue in this suit hoping for partner's singleton despites the low probability.   

What are most recommended leads playing UDCA?
Basiclly UDCA leads are made in 3rd with even and low with odd cards:
with K10532 the 5th card here is the "2";
with K1032 the 3th card is the "3";
with K104 the lead is the 3rd card here the "4".
But when we have no honor in the suit the lead is made in second higher:
with 97632 the lead is the "7"
with 8653 the lead is the "6"
with 862 the lead in this suit should be avoided
When there are sequences then lead is made in the top of sequence:
with J109xx the lead is the "J"
with 98762 the lead is the "9"
Special leads against NT contract not specific to UDCA:
with KQ10xx the lead is the "K" (promising Q10)
with AKJ10 or AKJxx the lead is the "A" (promising KJ)
Journalist leads against NT: the 10 promisse honor and jack denies
with J108xx the lead is the "J"
with KJ10xx the lead is the "10"
with A109xx the lead is the "10"
with AQ1053 the lead is the "5"
with AQ1093 the lead is the "10"
with AQ109x the lead could also be the Q thinking in Jx in dummy
with AK1053 the lead is the "5"
with AK1093 the lead is the "10"

Example of using UDCA system discard with count and suit-preference:

	Q8  AK3  KJ109  KJ109		bidding:   S     W     N      E          2     x      3  4  all pass   lead K           N-S Vul
AK7642  107  632  87	N W      E      S	1093  94  AQ5  76532	Team match  -  N-S and E-W play UDCA West leads K asking for count and East shows odd playing 10; West plays K and East now shows suit-preference to Diamonds serving 9; West plays 2 dummy serves low and East makes Q and plays A for down 1.  Without a suit-preference signal West may play trump and then N-S make 4.
	J5  QJ8652  874  AQ

In the reflex table E-W bid 4 doubled and North lead K asking for count and South serves 2 showing even. North plays A and South serves 5 showing suit-preference to Clubs. North plays 9 and South makes A and return Q coverd by K. Then North play J that is ruffed by J and West makes A. But now Q is upgraded for down 5.
Note: some partnership use a reverse suit-preference signal playing low to show interest in the higher ranking suit and playing high to show interest in the lower ranking suit.  
   
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LAVINTHAL system discard
This is a simple and very eficient method to show SUIT-PREFERENCE and in Europe where it is very popular they call it as McKenny. It was
Willian McKenny, an american bridge columnist died in 1950, that helped in the popularization of this method to signalize suit-preference, but it was during 1933-1934 that Hy Lavinthal (1894-1972) invented this system discard published only in 1963 in his book "Defense Tricks" where he explained his theory of defense.

This method can be applied in many situations in a bridge play but it is more used during the first discard excluding the discard suit and the current suit:
- if it is a high spot card discarded it asks for the higher ranking of remainders suits as the suit-preference,
- if it is a low spot card discarded it asks for the lower ranking of remainders suits as the suit-preference,
as we can see in the next table:

Declarer playing	my first discard	suit-preference	choosed between
	if Clubs low	Diamonds
	if Clubs high	Hearts
	if Diamonds low	Clubs
	if Diamonds high	Hearts
	if Hearts low	Clubs
	if Hearts high	Diamonds
Declarer playing	my first discard	suit-preference	choosed between
	if Clubs low	Diamonds
	if Clubs high	Spades
	if Diamonds low	Clubs
	if Diamonds high	Spades
	if Spades low	Clubs
	if Spades high	Diamonds
Declarer plauing	my first discard	suit-preference	choosed between
	if Clubs low	Hearts
	if Clubs high	Spades
	if Hearts low	Clubs
	if Hearts high	Spades
	if Spades low	Clubs
	if Spades high	Hearts
Declarer playing	my first discard	suit-preference	choosed between
	if Diamonds low	Hearts
	if Diamonds hith	Spades
	if Hearts low	Diamonds
	if Hearts high	Spades
	if Spades low	Diamonds
	if Spades high	Hearts

Playing STD with Lavinthal gives flexibility to make suit-preference signal helping to preserve important card in critical suit.
Example: East-West playing STD with Lavinthal 
              NORTH                        Bidding:
               962                    NORTH EAST SOUTH WEST
               32                        pass     pass     2      pass     
               Q1065                   2       pass     2      pass     
               Q1075                  2ST      pass     4      all pass   
                                             Lead Q 
WEST              EAST
lead  Q         10743  South makes A and plays K for 10 and 3 and
                      9         now EAST must discard and he is interested in
                       KJ92    EAST may discard 5 or 10 to show interest.
                       J974    Here 10 seems more safe card to be discarded.
             SOUTH            trick3 - Declarer plays K, West A and East 7
              AKJ              trick4 - West obeying partner plays 3 to 10 J A
              AK87654      trick5 - Declarer plays 8 to J 5 4          
              A8                trick6 - West plays 4 to 5 9 8                   
              K                  trick7 - East plays 3 to A 8 2
                                    and after playing all Hearts and K Declarer loses J
                                    for down 1 after this efficient defense
The 10 discard will exclude Spades (discard suit) and Hearts (Declarer suit current) so for the remains minors suit a high card means Diamonds;
In case of 5 discard this excludes Clubs and Hearts and so it remains Spades and Diamonds and a low spot card means Diamonds.

Revolving - another way to use Lavinthal is considering the suits in a circle then after Spades follow Clubs, after Clubs follow Diamonds, after Diamonds follow Hearts and after Hearts follow Spades. Thus a high spot card in a suit makes indication for the upper suit of discard card and a low spot card in a suit makes indication for lowdown suit.

Using Revolving a discard in Hearts if with high spot card means Spades and if with low spot card means Diamonds;
a discard in Spades if with high spot card means Clubs and if with low spot card means Hearts;
a discard in Clubs if with high spot card means Diamonds and if with low spot card means Spades;
a discard in Diamonds if with high spot card means Hearts and if with low spot card means Clubs.

In the example we must exclude Hearts so a discard of low Spades means Diamonds (jumping the suit exclude - Hearts) or a high card in Clubs means suit-preference to Diamonds.
In this case the 3 is the better discard.

Important: if you are the Declarer when opponent makes the first discard you should ask him how is opponent convention for discard and if they say Lavinthal you should be informed about which variation they are using (McKenny or Revolving).

Lavinthal method has a problem when you have nothing to indicate because in tesis the first discard is indication of suit-preference.
So in this case the player should use his middle card 5 or 6 to discard or make a suit-preference to an absurd suit. Then partner will understand that there is no good indication.

Of course the Lavinthal method needs to be use as a complement of STD or UDCA because it does not inform Count or Attitude.
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a)       NORTH
           AQx                  Bidding:
           Q10x                WEST NORTH EAST SOUTH
           AJ9                     1      1ST      2      2
           K10xx               pass    pass    pass            E-W STD
WEST           EAST
saída K        x          The lead of K probably with AKxxx allows West
                    J862     asks where East has honors. In this case East plays
                    Q10xx   J to show interest in Diamonds and also shows
                    9xxx      4 cards. The play of 2 would show 3 cards in but not necessarily Clubs interest and the play of 8 would shows 4 cards in Hearts but not suit-preference for Diamonds.
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b)          NORTH             Bidding:
              Kxxxx            WEST NORTH EAST SOUTH
              Q10x                                                1 
              Jxx                double   1        2      3 
              xx                   pass     3        all pass
WEST            EAST
saída K      xxx        The K, of course with AKxx asks for a counting in
                   J10642   Hearts because West wants to know if East has 4 or
                   xx           5 cards in Hearts for planning to play the A. Thus
                   Axx         East must play 2, so here there is no application to show suit-preference in Clubs.
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c)              NORTH
                AQxx           Bidding:
                x                 WEST NORTH EAST SOUTH
                AJ9x              2   double    3      4
                K10xx           all pass
WEST             EAST
saída A       x          West leads A maybe with AKxxxx and that allows
                     Q92     East to make a suit-preference to Clubs playing 2. 
                     Qxx     If East plays Q of course this is a suit-preference to
                     AQJxx Diamonds and the play of 9 would be to continue
                                   playing Hearts in case East has 4 cards in
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d)              NORTH        Bidding:
                 AQx          SOUTH WEST NORTH EAST 
                 x                 1      pass      1        pass    * 4th suit forcing
                 AQ109x     2       pass      2*      pass    ** 2 Aces with Queen
                  K10xx        3      pass      4nt      pass   
                                      5**  pass      6       all pass
WEST             EAST
saída A       Jxxx     After the lead of A East must ask for continuation i                   KJ952   in Hearts to preserve his Jxxx in trump suit, but
                    x           can't play K because that asks for Diamonds, so he
                    Qxx       must play the 9 as an attitude signalization.
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e)                NORTH     Bidding:
                  9xx         WEST NORTH EAST SOUTH
                  xxx          pass    pass     1       1     
                  xx              2       2      pass     3          
                  AKQJx     pass     4      pass    pass   
                                   double  all pass  
WEST             EAST
saída 3        xx         After the lead of Clubs it is clear that West has 
                    KQ952   singleton Clubs and has a trump stopper, thus it is  
                    AK         fundamental to East to shows where is his entry. 
                    10852   East must show his entry playing the 2 as
                                    suit-preference for Diamonds denying A.
If West has A then after Declarer play trump. He makes A and shift to Diamonds and East making the K plays little Clubs for ruff. After the continuation in Diamonds East plays again Clubs for another ruff for down 2.

Note: when you inform partner about your suit-preference this may change Declarer's plan to play and sometimes you may be throw-in by a advanced Declarer, so you must be careful, think twice before giving this information to partner and of course to Declarer.

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ODD-EVEN (O/E) aka Roman system discard
This method made by the italian champions in the years 60 it is an improvement in the Lavinthal method and can be used together with STD or UDCA because it applies for ATTITUDE and SUIT PREFERENCE but not for COUNT (to show even or odd number of cards). So in your first discard o/e is a good option for partnership.

In the first discard o/e makes indication of his suit preference:
- an odd card discard shows SUIT PREFERENCE for this suit, so if you  discard Clubs 9, 7, 5 or 3 you are saying to your partner that you have honors in Clubs;
- an even card discard says to your partner that you don't want this suit;
- and in complement if you discard a high even card in this suit this means you want the high side suit excluding this suit and trump suit, so if the trump is Spades and you discard high Clubs then this means between the remanining suit Hearts and Diamonds you want Hearts not Diamonds;
- and if you discard a low even card in this suit this means you want the lower side suit excluding this suit and trump suit, so if trump is Spades and you discard low Clubs this shows Diamonds interest, not Hearts.

ODD-EVEN discard must be played at the first discarding oportunity as an ACBL rule for those play bridge under ACBL events in U.S.

Dodds discard, used in England, is just a change from even to encourage and odd to discourage (UDCA in attitude). So playing against european partnerships ask their system discard in detail if they tell you just O/E.

Example of effectiveness using O/E system discard:

	J83  K2  8654  KQJ		bidding:   S     W     N      E  1nt  pass 3nt  all pass     lead 4
A10742  73  Q9  9876	N W      E      S	6  AQJ104  10732  532	After west leads 4 Declarer makes 9 and plays 5 to dummy Jack but West makes A and East must discard now: If East is playing just STD he must call for Hearts playing  10 and partner will shift to , East makes only 3 tricks because Declarer has 9xxx. But playing O/E he discards 10 to call for Hearts and after partner 7 N-S goes down two (1 Spades + 5 Hearts)!
	KQ95  9865  AKJ  A104

Note: the 10 discard deny interest in Diamonds and of course in Spades asking for between Hearts and Clubs the higher ranking suit (Hearts).

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SMITH ECHO

This interesting signal apply only against opponent NT contract to show if defender likes or doesn't like the lead made by himself or by partner. So when Declarer plays another suit each player may show to his partner if he should continue the lead suit by playing a high card or asks to shift to another suit by playing a low card.

Example: the partner of opening leader using Smith Echo deny interesse in continue playing a low card in Declarer's developing suit.

	94  KQ7  AJ4  KJ982		bidding:   S     W    N      E                               1    pass                 1 pass  2    pass                3nt all pass             Lead: 6
A10762  1092  653  A4	N W      E      S	J83  A43  9842  765	South wins the J with K and plays Q for West's A and East serves the 3. West doesn't know who has Spades Queen but playing Smith Echo East served low Clubs so he doesn't  like partners lead - this means he does not have the Q or 4 cards. West must find an entry in East's hand and the only possible solution is A with partner!
	KQ5  J865  KQ10  Q103

Example: Opening leader using Smith Echo shows his partner not to continue in lead suit by playing a low card.

	KQ4  872  105  AJ972		bidding:   S     W      N      E                1nt  pass  3nt  pass               pass pas                    Lead: 6
62  K1064  AQ92  863	N W      E      S	J983  J93  J864  K5	South wins the J with Q and plays Q for West 3 and East's K. East notices that West serves the 3 saying he didn't like his suit (Smith Echo) So East concludes that Diamonds is the only shift suit possible to defeat and if Declarer has the Kxx he must play the J to defeat this contract!
	A1075  AQ5  K73  Q104

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DISTRIBUTION SIGNAL

The use of signals during Declarer's playing trump is usually to play high-low to show 3 cards and interest in ruffing another suit, but the danish theoric bridge player Helge Vinje in his book "Defensive Play in Bridge" published in 1979, proposed another meaning for signalling trump.

Vinje suggests signaling trump to show our type of suit distribution as an informe that could help deduce partner's and Declarer's distribution of cards.
 
In the 39 possible distributions of the suits in any bridge hand there are two groups: 3 suits with odd number of cards and 1 suit with even number of card (4333 5431 5521 7321 7510 ...) or there are 3 suits with even number of cards and 1 suit with odd number of cards (4441 4432 5422 6421 7222 8320...).

So we can classify these distributions in 8 sub-groups:
 EVEN-SPADES (ES) => 1 Spades suit with even cards and 3 suits odd
 EVEN-HEARTS (EH) => 1 Hearts suit with even cards and 3 suits odd 
 EVEN-DIAMONDS (ED) => 1 Diamonds suit with even cards and 3 odd
 EVEN-CLUBS (EC) => 1 Clubs suit with even cards and 3 suits odd
 ODD-SPADES (OS) => 1 Spades suit with odd cards and 3 suits even
 ODD-HEARTS (OH) => 1 Hearts suit with odd cards and 3 suits even
 ODD-DIAMONDS (OD) => 1 Diamonds suit with odd cards and 3 even
 ODD-CLUBS (OC) => 1 Clubs suit with odd cards and 3 suits even

Obviously it is impossible to find a sub-group with 2 suits having odd number of cards and 2 suits having even number, or a sub-group with 4 suits with even number of cards or a sub-group with or 4 suits with odd number.

So defending against a suit contract if defenders playing distributional suits convention when Declarer plays trump by convention a defender when play his trumps cards high-low inform partner that have only one suit with a number of cards even and when playing trump low-high inform partner that he has only one suit with an odd number of cards.
               HIGH-LOW => EVEN ODD ODD ODD
               LOW-HIGH => ODD EVEN EVEN EVEN

Defending against a NT contract we may use these signals high-low for even and low-high for odd in the first suit developed by Declarer.

Of course there are ocasions that we are unable to signal high-low but maybe in half occasions this will be possible and then this will allow partner deduce Declarer's distribution of cards and so keep the correct suit guarded when Declarer is trying to make a false squeeze playing his long suit.

Undertanding Declarer Distribution Could Be Important for Defense?

Supposing you want to know if Declarer is singleton or dubleton in a long suit in a dummy (KQJxx) without other entry when you have Axx and you know that Declarer may have 1 or 2 cards in this suit. So if you know your partner's distribution and dummy and your cards then you may deduce in what suit Declarer is singleton to decide for holding or serving your ace.

	A52  84  753  KQJ87		bidding:   S      W        N       E                                  pass  pass                1     1      1nt   pass                4   all pass                  Lead: K West leads K, dummy serves low, East serves low and Declarer serves low. In trick2 West continuing Spades with the Jack, dummy makes the trick with A and East 10 drops.
KQJ93  65  1094  A63	N W      E      S	104  932  KQJ82  J52
	876  AKQJ107  A6  94

trick03, trick04 and trick05 Declarer plays trump and West that is even (only one suit even) to show type even hand serves 6 and 5 (high-low). East  that is also type even hand serves 3, 2 and 9.
Analyse: West knowing that East is even in Spades after 10 drop may now infere declarer distribution as 3 cards spades, 6 cards hearts and dubleton in both minors to also be even because East should be tripleton in Clubs and so have 5 cards in Diamonds. East with 7 cards in Diamonds should bid 3 Diamonds and not pass. So declarer's hand is 6322.
Trick06 Declarer plays 9 and West let it run to King Clubs for down 1 because now Declarer loses 2 Spades, 1 Clubs and 1 Diamonds.

The information of suits distribution prevent a possible blunder in discard

	A84  J732  J43  J32		bidding:   S      W      N        E                     2  pass    2*   pass                 2  pass    4     pass                 4nt pass    5** pass                 7  all pass Lead:7  =>waiting **=>1keycard        Declarer plays 3 times trump and West plays 7 6 6 and East play 2 3 5 so West shows to be even in Spades suit and East shows to be odd in Spades suit.
76  Q65  Q75  109876	N W      E      S	532  10984  10986  54
	KQJ109  AK  AK2  AKQ

Analyses: West knows that his East has 3 even suits and deduces that East hand is 3442. Possibly 3262 or 3244 seems not like  Declare's hand.
So it is clear to West that Declarer has AK second and AKx then West is now prepared to keep his Q75 and not guard his Q65.

Declarer also may use defenders sinaling to take decision.

	A64  K74  K65  K972		bidding: S     W       N      E              1   pass    2  pass              2nt  pass    4  all pass  Lead: Q Declarer covers Q with K, East serves 7. Declarer plays low Hearts to K with West serving 2 and East serving 3. Declarer plays low Hearts to J that loses to Q with East serving 8. West plays 2 and North makes A, East 3 Declarer plays A with West serving 10 and East serving 9 (W-E playing STD).
QJ92  Q102  102  Q1053	N W      E      S	10753  83  QJ986  86
	K8  AJ965  A72  AJ4

Analyses: Both defenders play low-high showing only one suit with odd number of cards and so West showing 3 cards in Hearts means that all west other suits have even cards.
Now Declarer plays 2 and finesse Queen playing J that loses to Q.
West plays J and Declarer ruffs and play A then he plays 4 West serves 5 and Declarer must decide for another Clubs finesse or for 10 drop.
Declarer trusting in defenders sinalling that West is odd and so must have 4 cards Clubs and then finesse the 10 playing 9 to make 5. 

Here defenders knowing suit distribution can't do anything against the correct play of the hand by Declarer

	QJ4  874  K65  KQ107		bidding:   S     W       N      E                2   pass    2  pass                2   pass   4nt  pass                5* pass   7  all pass    Lead: J * 5 keycards denying trump Quees Declare wins the J with A East serves 2. Then Declarer plays 3 times trumpes (Spades) and West serving 6 2 9 and East serving 5 7 8. So West shows 4 suits with even cards and East shows 3 suits with odd cards.
62  QJ109  Q1042  863	N W      E      S	875  632  J86  J952
	AK1093  AK5  A72  A4

Analyses: Declarer knows that West has 4 cards but don't know if West has also 4 cards or 4 cards. In case West has red suits and East has 4 cards Declarer should play for double squeeze with Diamonds central suit.
For West his partner must guard Clubs and need to have Jxx to guard this suit against a squeeze in the reds.
Thus it will be easy for West to keep guard in Hearts and wait with his guard in Diamonds until possible.  
For East it will be easy keep guard of Clubs but if West discard 2 times Diamonds he will be squeezed between jack Diamonds and Jack Clubs.
tricks - South West North East
trick01 -   A      Q    4     2
trick02 -   3       6     J     5
trick03 -   9      2     Q     7
trick04 -   A      9     4     8
now Declarer test drop of Jack Clubs
trick05 -   A      2     7     2
trick06 -   4      6     Q     5
trick07 -   5      8     K     9
trick08 -   K      10   7     3
trick09 -   K      2     5     6
now Declarer will play the squeeze card          
trick10 -   10    4     8      ? <= East blows up and discards 6

                  8  
                  K6
                  10                  
    J                      J86
    Q104                J              
                  10
                  A72
trick11 - 2      10   K    8
trick12 - A      Q    6    J
trick13 - 7      J     10  J  
contract 6nt done                       

Here defenders have a little advantage knowing the suit distribution and may discard more comfortably when Declarer plays his long suit.

	74  32 KQJ6543  97		bidding:   S     W      N      E        E-W Vul                                  3  pass               6nt   all pass                   Lead: Q
K932  QJ94  102  K54	N W      E      S	Q1084  765  92  J1032	Declarer wins the Q with A, East serves 5 showing possibly 3 low cards, Then Declarer plays AK with West-East serving 102 and 92 both showing 3 even suits.
	AJ5  AK108  A8  AQ86

Analyses: East must guard his 4 cards suit and West must guard Hearts suit already knowing that East has both black suits in 4432.
Declarer planning his 12a. trick maybe in Clubs finesses or in a throw-in.
West deduces that Declarer has 4432 with also 4 cards in Hearts 3 cards in Spades and 4 cards in Clubs. But for East it's not clear yet if Declarer has 4 cards or 4 cards because West may have 4423 or 3424.
But both E-W already assume that Declarer has all aces but only the Heart King so 11 tricks. They also deduce that Declarer should have the Q but not the J because with QJ makes 12 tricks.
Declarer may consider that East may have both blacks 4-4 so the probability for King Clubs in East is a relation of 4 by 3. West knows that also and may discard one or two Clubs if necessary.
Declarer will discard 2 Clubs 2 Spades and one Hearts, so during the play of the Diamonds West will discard Hearts only after Declarer discards Hearts and will discard Spades kepping K dubleton or singleton because after Declarer playing for Clubs finesse West need to exit with the Spades King.
Defenders need poker face during the discards to defeat, because they already know many informations about suit distribution.
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HOW TO SHOW PARTNER IN WHAT SUIT YOU HAVE AN HONOR?

Suppose declarer is playing a contract and your partner leads in a suit where you signalize no interesting. One way to inform your partner in what others to suit you have an high honor is during declarer play of his suit use it to indicate your have an high honor:
low ranking => you play low and high in declarer's suit
high ranking => you play high and low in declarer's suit
So, if your partner need make decision he will now have a information.

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ENCRIPTED SINALING

It is an ingenious method to avoid Declarer to know if opponents are using STD or UDCA in their signals.

How encripted sinaling works?
The defenders vary their signaling procedure according to a formula that is revelead to the Declarer but Declarer can't decode the signaling because a variable key depends on some spot cards in the defenders hands. 

How we do that?
Well we can imagine many ways, for example, when Declarer ruffs a suit or discards any card in a suit, only defenders know some information about this suit.
So we may establish some spot cards like: "8", "9", "'10" and "J" as our coded cards and we may define that the player with even number of that spot cards (0, 2 or 4) will use STD in their sinalization and the player with odd number of that spot cards (1 or 3) will use UDCA in their sinalization.

Before the cards start to be played we say to opponents that our signal is  STD or UDCA (you choose the start system discard) but it will change based the even or odd spot cards we have in the suit Declarer's ruff of discard a card.

Example1: E-W use STD and during the card play changes to encripted signals

	QJ8  876  875  AK84		bidding:   S     W     N     E     N-S Vul                1    2    4    5     E-W nVul                5   all pass            Lead: A West leads A and East serves 4 West plays 6 East K that is ruffed. So Diamonds became the suit with the spot cards and West has J 9 (even) so he is now STD and East has 10 (odd) so he is now UDCA. Declarer plays twice trumps and East play 3 (UDCA) showing high honor in Hearts but Declarer can't know if he means STD or UDCA.
72  Q1065  AQJ96  75	N W      E      S	6  A943  K1042  J1032
	AK109543  KJ  3  Q96

Declarer has 10 tricks and may find 11th in the Clubs 3-3 or finding the  position of A.
West knows now that his partner probably has the A so he may discard 2 cards in Hearts if necessary.
Trick# South West North East
trick01  3      A     5     4
trick02  3      6     7     K
trick03  A      2     8     6   
trick04  4      7     Q     3  <= East using UDCA shows Hearts honor        
Declarer plays 4 more trumps keeping one trump before playing Clubs
trick05   K     Q     J     2
trick06   10   J      6    10
trick07   9     5     7     4 
trick08   Q     5     4     2
trick09   9     7     A     3
trick10   6     6     K     9
the 3 last cards are:
                  8
                  8
                  4
   Q10               A9
   9                    J
                  5 
                 KJ
and now North plays 8 East serves 9 and South must decide
   Who Knows What Declarer Will Play?

How partnership define STD or UDCA against NT contract?
Example2: Opponent are playing 3nt and West has:
West:     Q83 J1098 Q96 754  
dummy: J83 1063 872 AKQ10
West leads against their 3nt the J and Declarer makes the A and play Clubs to dummy AK serving the "2" and the "7" and in the Q Declarer discard a low Hearts with W-E serving Clubs but the Jack and the 9 did not apper.

So Clubs become the suit for our spot cards and West have zero spot cards so West will use STD.
Declarer + dummy has 1 spot card the "10"
East => has the "J" and the "9" so he will also use STD.

Thus it is an easy method and of course this demands training with our regular partner for a long period to have total assimilation, but depending on the country we are playing encripted system discard is not allowed. If there are no restrition this needs a pre-alert explanation with a written card avalaible to be readed at any time during the game.

Finally to use encripted signaling a partnerhsip should define their spot cards and be prepared to explain this system discard before using it, not in a tournament but during a teams context. Of course when asked you explain your methods already written in a card, but by no means do you have to explain a particular card discarded or served.

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WHAT IS THE RECOMMENDED METHOD / SYSTEM DISCARD

Of course it is the method that both partners understand well and are comfortable to play. So make sure that partner is on the same wave length discussing system's details and maintaining conventions writed and aproved by both players.

There is no right answer to choose a discard system because some work well in one hand but not in another.

Some adeptus of UDCA argue that UDCA is better because avoid high card discard and so they encourage with low cards keeping his high cards. In other hand adeptus of STD augue that playing UDCA sometimes we need serve a high card to discourage continuation but that high card will provoke a lose trick.

All systems discard have configurations where there are no perfect signalling solution for a specific configuration of cards.

Playing STD in rare ocasions we may have KQ2 in a suit and then partner leads the ace of this suit to see dummy's cards to decide what to do hoping for partner's help with an attitude indication. But supposing dummy shows J106. What should we serve? Having KQ2 if you encourage playing the King partnership will lose a trick and playing the 2 we will inform partner to shift to other suit. So this is an insolved problem for Standard System.

So we change the system discard for UDCA and now when the same situation occurs we will  encourage playing the 2 and keeping KQ.

Next weak partner having AK43 leads Ace and dummy shows J97 and our cards are J102. We now are playing UDCA so we need to discourage the continuation, but if we play the 10 then Declarer having Q65 will make his Queen because a possible finesse was created.  If we play the 2 encouraging the continuation partner play King and Queen becomes a top card.

Thus playing STD or UDCA, both, in rare configuration may be faced with no solution for a correct signal. 

So we change the system discard to ODD/EVEN, supposing that italians must have a true reason (not only to sell books) to use this system discard.

Then in next having AK75 partner leads the Ace and dummy shows 973 and our cards are Q82. We are now playing O/E and we want the continuation having Q82 but we don't have an odd card to ask for continuation! So we must play an even card that will be interpreted by partner as a suit-preference but we also don't have a good suit to show interest for a shift by partner.

The italian champion Eugenio Chiaradia (1911-1977) 6 times winner of Bermuda Bowls (1957, 1958, 1959, 1961, 1962 and 1963) when living in São Paulo - Brazil coaching the brazilian team, taught that we should not make signaling always but only in specific moments helping partner to defeat the contract. He says: discard always low cards you don't need during the current suit always make signals.

Conclusion: a partnership must use STD or UDCA as system discard and use signaling only when necessary, but partnerhip should know how to apply a Lavinthal discard to orient defense or make use of agreements  for better defense using, for exemple, Jack Denies or Smith Echo against their NT contract.

When you are the Declarer you should disturb their signaling using false discard (playing a middle card or high honor) to make more difficult for opponents to understand their distribution. There are many books written about false cards.
 
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