The Swiss Convention is designed to cover hands which are too strong for a direct raise to game in the opener's suit, but not suitable for a Delayed Game Raise because of the absence of a good side suit ... a jump to4C or 4D is used to show a raise based on high cards rather than distribution" Typically, 4C shows something and 4D denies it. There are many possible "things" that can be shown. A common one was that 4C showed two Aces and a side suit singleton (4D showed the Aces but no singleton) This requirement of two Aces meant that some hands could not use Swiss. If using this version, however, a rebid of 4NT asks for Kings, not Aces. After a 4C response (2 Aces and a singleton) a 4D bid asks for the singleton, with a return to the trump suit showing a diamond singleton (This is from "Acolites Quiz" by Rhoda Lederer) Example hands from Crowhurst: KT KQ83 1H - ? QT65 A72 Note that if you guaranteed two aces, you would have to bid 2D then jump to 4H with this, which mis-describes the quality of your diamonds. AQ3 KQT85 1H - ? A95 Q7 This hand should Swiss and then cue bid 4S if partner returns to 4H

A now obsolete method of conventional raises after a major suit opening bid. I found two references in old bridge books which mention Swiss raises: [1] P.Boender, "Slamconventies", 1968 (in Dutch) [2] H.Kelsey, "Slam Bidding", 1973 (in English) Both books claim to describe the latest in slam bidding tools. [1] contains a translation of an article by a certain Dr. Weber in Bridge Magazine and claims that this is the original version of Swiss: 1 M - 4 C : 11-15 points, 4+ card support, 2 aces, no good side suit. - 4 D : 11-15 points, 4+ card support, 3 aces or 2 aces and the king of trumps or 2 aces and a void, no good side suit. Other hands with support are either shown through a jump shifts or a delayed game raise (1M-2m,2?-4M). The latter sequence is strong in Stone Age Acol, not a sign-off based on fast arrival. Over the Swiss bid, opener returns to the trump suit if he has no slam interest, otherwise he bids 4D over 4C or 4 of the other major over 4D. 1 M - 4 C 4 D : Responder bids a suit in which he has a singleton, without a singleton he returns to the trump suit. 1 M - 4 C 4 D - 4 H/S/5C/5D 4/5 NT : Opener asks for aces according to the CRM principle: 5(6) C shows the red or black aces, 5(6)D the major or minor suit aces, 5(6) H aces in the round or pointed suits. 1 H - 4 D 4 S and 1 S - 4 D 4 H : Responder bids the suit in which he has a void or returns to the trump suit without a void. 1 H/S - 4 D 4 S/H - 4S/5C/D/H 4/5 NT : Asks for aces with special responses: 5(6) C : 2 aces red or black OR 3 aces missing the CA 5(6) D : 2 aces major or minor, OR 3 aces missing the DA 5(6) H : 2 aces CH or DS, OR 3 aces missing the HA 5(6) S : 3 aces missing the SA For example: K 10 x x x Q x x x x A x x x x A x x x x K Q x A x x 1 S 4 C 4 D 5 D 6 S

"Slam Bidding" lists 8 variations of Swiss. It also claims that the convention is of Swiss origin (as we could have guessed from the name). The 8 variations are:

1. Aces Swiss or original Swiss, the convention described above.
2. Unspecific Swiss: 4D is simply stronger than 4C, there are no ace requirements.
3. Double Barreled Swiss: 4C/D show the hands as in Aces Swiss but any point count. With 15+ responder bids again after 1M-4m-4M
4. Trump Swiss: 4C denies 2 top honors, 4D shows at least 2 top honors in the trump suit.
5. Singleton Swiss: just another name for splinters.
6. Super Swiss. 3S/3NT/4C/4D are all raises of 1H showing: 1 H - 3 S : A void 3 NT: A singleton 4 C : 2 or 3 aces, no singleton/void 4 D : less than 2 aces, no singleton/void.
7. Minor suit Swiss. 3H/S are strong raises of 1C/D opening bids.
8. Reverse Swiss. 4C/D re-bids are artificial support showing bids after 1 minor, 1 major or even 1 minor, 1 of a suit, 1 of a major.

The problem that all these Swiss variations have in common is that they either waste a lot of bidding space and/or require very specific hands for the Swiss bids. In all examples that I have seen one can easily transform make able slams into hopeless ones (or visa versa) by swapping a honor or two without changing the bidding sequence.

Perhaps that's why these bids are out of fashion. IF you play the bid as very precisely defined -- 12+-15-, no singleton or side suit, with 4+ trumps, 4C showing four pieces with two of the top three honors, or five with Ace of King -- this can be a very useful bid. With a nine card fit you rarely want to play in NT. Also, if you add a relay to get a more precise definition of the trump holding, the bid, although rare, can be very powerful. And I know of no better way to use these bids in a standard 2/1 system (assuming, of course that you use 1 step above 3M to show a splinter hand). Jay is correct that Swiss is out of favor with splinters being much more common. Users of Swiss now tend towards the combination which Jack seems to be alluding to which is called Fruit Machine Swiss which combines splinters and Swiss. The system of Swiss raises that I've used recently is 'Super Swiss' over 1H 3S - Void 4C - relay (4D-diamond void, 4H-club void, 4S-spade void) 3NT - Singleton 4C - relay (4D-diamond sing, 4H-club sing, 4S-spade sing) 4C - Two aces 4D - One ace over 1S 3NT - Void 4C - relay (4D-diamond void, 4H-heart void, 4S-club void) 4C - Singleton 4D - relay (4H-heart void, 4S-diamond void, 5C-5S- club void, Blackwood resp) 4D - Two aces 4H - One ace (Over the response to the relay 4NT is blackwood).