This being primarily an intermediate/novice bridge blog, this post on "splinter" bids will be a basics refresher. A splinter is a game force supporting response to an opening bid that, in addition to solid support, shows a singleton or void in responder's hand. The splinter is shown by making a three level jump in the suit in which you have shortness. Thus 1 spade/4 clubs would be a splinter bid showing 4 spades and a single or void in clubs. Having said that, even in the basic version, there are understandings that you need to have with your partner. Here are some points to go over:
1. While some partnerships splinter in all four suits as well as no trump, your life will be simpler if you limit your splinter bids to responses to major suits.
3. The support requirement for a major suit splinter is 4 or more cards in the major suit. The main thrust of splinters is to inform opener of your shortness so that he will know that he can trump losers from his hand in your short suit. Since opener may have 3 or more losers in the suit that need to be ruffed, a minimum of 4 trump is required.
2. Most authors recommend a hand in the range of 11-14 points. This is a nice guideline, but in reality what you really need is a hand that you want to play in game against a minimum opener. In making that analysis you should take into account you that already have a 9 card fit and favorable distribution (the single or void). Since we are not going to play this hand in no trump, 25-26 high card points are not required. Shape and fit will be more telling, and I would venture a guess that many splinter hands are undervalued and not "splintered" simply because responder is relying only on high card points as a standard. If you are looking for a finite answer in high card points, it is not there. Surely a hand such as AKxx,KJxx,Qxxx,x merits a splinter bid opposite either a spade opening bid. On the other hand I would also splinter with AQxxx,Kxx,xxxxx,void.. Developing bridge players hate the word, but is is "Judgement."
Before going on I should explain why there is an upper limitation on the bid. If responder's hand is 15+ points, his hand is likely larger than opener's hand and responder needs to take charge and become the captain of the ship. Instead of using a splinter bid, use Jacoby 2 NT and conduct your own investigation. If you are headed for slam, there will be an opportunity to cue bid your shortness later.
3. Most authorities will advise not splintering if your singleton is an Ace. Others extend that to a single King as well. Visualize that opener is trying to evaluate his hand after you splinter. He does this by trying to develop a sense of how much duplication of values exists is in the suit in which responder has shortness. An ideal hand for opener is to have 3 small cards in the short suit. That means that all of opener's high card points are in the other three suits. High card points in the other suits are called "working points." In my two responder hands shown above, the AKQJ of clubs are "wasted values" since they will take no tricks. For opener and his partner the deck has now shrunk to 30 high card points. If they have 26 of those 30 working points, they may have a small slam and not just game. The less opener has in values in the splintered suit, the stronger the value of his hand.
On the other hand, if opener has KQxx in the short suit or QJxx, he will discount his hand thinking that those points are wasted values. You can trump 2's and 3's just as easily as King's and Queen's. I think it easy to see if responder has the Ace or King as his splinter, he may have led opener to the wrong analysis. In fact, opener's subordinate honors will be very useful opposite either of the holdings that I cited.
4. Should you splinter if you have a good a good outside 5 card suit? Assume you hold Jxxx, Kxx, x, AQJxx and partner opens 1 spade. (Please don't tell me that I don't have enough points to splinter). World Champion Mike Lawrence tells us to show the source of tricks by bidding 2 clubs and then show the support and distribution later if there is space. Marty Bergen, on the other hand, would bid 4 diamonds showing the splinter. In his mind there is nothing as important as telling partner immediately that you have four card support and shortness in diamonds. Although I like Mike's approach, you are going to find that in some auctions it is hard to get three separate messages to partner in the space that you have. If you are not going to splinter, there needs to be a partnership agreement as to how the auction should proceed. Hopefully you are playing 2/1 so that a 2 club response would be a game force. It doesn't matter what suit opener bids next, but say it is 2 spades. Since the auction is already in a game force, and you can show a diamond suit with a bid of 3 diamonds, so a bid of 4 diamonds should be a splinter. Does your partner understand that? I like the advice of one writer: "If a bid at one level lower would be forcing, then a bid of a new suit at a higher level is a splinter."
5. Opener may also use splinter bids on his first rebid. The bidding sequence might be 1c/1h/4d, showing four card support for hearts and a single or void in diamonds. In this sequence opener must have a very good hand with strong hearts support since all partner has promised is 4 nondescript hearts and 6 hcps. Since responder is still an unlimited hand, opener wants to invite to slam if responder has extra values. A more likely scenario is a 2/1 sequence like 1h/2c/3d showing 4 clubs and a single or void in diamonds. Why would 3 diamonds be a splinter? Because we are already in a game force and a diamond suit could have been shown by a bid of 2 diamonds. Since we know that responder has at least an opening hand, the values for showing a splinter can be reduced.
6. Partner has splinter on his first response. I have a minimum hand. I simply bid 4 of the major warning partner of my limitations. Responder is now the captain of the hand. If I am interested in exploring slam, I must make an up-the-line control showing bid in some other suit.
7. As usual, you need to know when "splinters" are "on" or "off." The classic rule has been that they are "on" over doubles and "off" if there is an overcall or if partner is a passed hand. If I were to alter that rule, I would have splinters "on" by a passed hand. Since I am aggressive about splinters, I can visualize hand that I might splinter with that I would not open. (J10xxx, x, KQJx, Kxx). When partner responds 2 hearts, what is your rebid? If partner has as much as AKxxx, xxxx, Ax, Qx we will make 4 spades. On the other hand, if he has AKxxx. A, Axxxx, Qx, six spades cannot be stopped. When you think about it, why would a passed hand need a splinter level response if it were not a splinter?
Are splinters new? Heavens no. Dorothy Hayden Truscott (herself a multiple champion) came up with them decades ago. They have simply withstood the test of time because in the end, shape always tells.