Walsh Transfer System (Including Walsh Relays).

There are several different versions of Walsh transfer. This is the one I have found the most often. As with any other detailed bidding convention you should discuss your system with your partner. (A) It uses 4-suit transfers with pre-acceptance bids in ALL suits. After 1NT
2D is a relay to hearts. It may or not show hearts. See below.
2H --> spades
2S --> clubs
2N --> diamonds

To invite in NT one starts with 2C Stayman which MAY NOT show a 4 card major. Then follows with 2NT. I discuss Stayman auctions below.
The pre-acceptance bids are as follows:
After a transfer into a minor note that there is an intermediate step between the transfer and the suit. If opener refuses the transfer and bids the intermediate step it is a pre-accept. It says "Partner. If your hand is an invitational one based upon a long minor, I would accept the invite and bid 3NT." It shows GOOD supporting honors in the suit.
After a transfer into spades:
Opener can refuse the transfer with a variety of maximum hands with 4 trumps. After 1N-2H:
3C, 3D, and 2NT all show working doubletons in side suits. A working doubleton is a doubleton in which you have no wasted secondary honors. xx, Ax, Kx, AQ are examples. Qx, Jx, QJ are not.
3C and 3D show working doubletons in those suits. 2NT shows a working doubleton in hearts.
After such a response, 3H by responder is a re-transfer.
3S shows any other pre-accept.

After a relay into 2H:

The only preaccept is 2S. The reason for this is given below. It simply shows any max with 4 trumps.

(B) Rebids by responder after a transfer is accepted without pre-accept.
2S-3H shows at least 5-5 slam try in H,S

2S-4H 6S, 4H. No slam interest

2H-3S 6H, 4S, No slam interest

2H-2S *Special* Starts relay sequences. See below

Transfer into major, then bid minor --> Forcing. natural. May be slam try but initially treated as simply seeking best game.
Transfer into major, then jump to 4 of same major --> 1 suited slam FORCE in that suit; Opener can initiate a series of asking bids, or can signoff in 6.
Transfer into minor, then bid major. --> Shows at least 6-4. At most invitational. Requires opener to raise with 4 card support. Opener can also pass or bid 3NT according to his hand.
(C) Stayman.

All responder hands with at least one major and no 6 card suit anywhere start with Stayman. Responder may also bid 2C with no major, intending to rebid 2NT to show an invitational NT hand.
? = 2NT; invitational, may or may not have a major
? = 2H; 5 hearts, 4 spades, invitational
? = 2S; 5 spades, 4 hearts, invitational
? = 4D; 5-5 majors. Choice of game, no slam interest. (called Weissberger)
? = 3 of minor; unspecified 4 card major and 5 card minor. Forcing
? = 3 of major; Smolen. Shows 5-4 with 5 in the OTHER major.
? = 4C; Minor suit slam try; shows at least 4-4 in minors. Opener signs
off in 4NT if not interested. If interested, opener makes a bid, based on steps that shows hand pattern. It can be followed by a variety of asking bids. I won't discuss these sequences here.

? = 2S; natural, invitational with 4 spades (assumes response was 2H)
? = 3 minor ; natural and agrees on bid major. Slam try
? = 4C; Gerber
? = 4 of other major; = 6 keycard Blackwood, counting 4 aces & both major suit K's.
? = 4D; Denies interest in major. Minor suit slam try, at least 4-4. same as 1N-2C-2D-4C above.
Note that minor 2-suit slam tries all start with Stayman, then jump to the 4-level depending on partner's response. (C) Walsh relays All responder hands that are slam tries with a long suit (and perhaps a second suit) start with a relay sequence. Long suit = at least 6 cards. Here are the sequences: 1N-2D 2H-2S This sequence cancels the transfer into 2H. 2S here forces 2NT by opener. Now responder describes his hand. It is because of the possibility of this sequence that the only allowed pre-accept in hearts is 2S. If: 1N-2D 2S then responder now bids 2NT as a retransfer into hearts. Any other call over 2S by responder has the same meaning as in the sequence: 1N-2D 2H-2S 2N-? The responses are as follows; 3C,3D = broken suit slam try in C,D; may have second suit 3H,3S = good suit slam try in C,D; may have second suit; good suit means 2 of the 3 top honors minimum. 3NT = unspecified solid suit (AKQxxx or better); opener bids 4C to ask the suit, or bids 4D to ask for OUTSIDE controls; starts a variety of asking bids 4C,4D = broken suit slam try in Hearts and spades respectively. 4H,4S = good suit "" 4NT = solid suit slam FORCE. promises extras outside the suit (D) 1NT-3level bids One can use whatever you like for these, so long as they don't duplicate the meaning of other sequences above. I use 1NT-3x to show a 4 x 1 slam try ; x is the suit BELOW the short suit; opener can relay in the short suit to ask for controls [step responses. 1st step = 0 to 3 controls], then follow with other asking bids [which I will not describe]