A couple of years ago I took a show of hands while speaking to the ABTA summer conference about the (related) auction 1NT-2C-2H-4C. The group was pretty much divided between those who would treat it as Gerber and those who thought it was a splinter. Truscott, in ‘The Bidding Dictionary’ states that in this sequence most experts would treat 4C as a splinter (since a suit has been bid naturally), while after 1NT-2C-2D, 4C would be Gerber. He notes this leaves 1NT-2C-2D-4D undefined… He avoids discussion of your sequence, except to note that for some, all 4C bids are Gerber, leaving 4NT as natural (which I would play it as, I think). And yes, in the system you describe you have no way to agree hearts in a forcing auction. Which is why you and I played (1) Two-way Stayman (2) over 2NT, a special bid to agree the suit and make a slam try as in 2NT-3C-3H-4D.

While it may occasionally result in an unwarranted minus, the “textbook” way to agree a major and invite slam quantitatively is to raise Opener’s 2M to 5M – hardly ideal but the price that’s paid for not having a below-game method. Also why some play a rebid of the other major as artificially agreeing Opener’s major, forcing to game and inviting slam (in the absence of some sensible system like 2-way stayman) so that 1Nt-2C-2H-2S shows a heart fit, game force, slam invite as 1NT-2C-2S-3H does the same relative to a spade fit. This leaves 4C in your problem sequence as Gerber and 4NT as a no-fit, quantitative slam try. If you want to ask aces (keycards?), you first set trumps and then use 4NT.

OK, I got intrigued by this and did some more follow-up. Eddie Kantar in the 4th edition of ‘Roman Keycard Blackwood’ comments that using 1NT-2C-2maj-4C as RK Gerber is a ‘useful agreement’, allowing 4NT to be natural ‘if that agreement is in place’. This example has been eliminated in the (just-published) 5th edition. So I went to Bridge World Standard, where 1NT-2C-2D-2maj is Smolen (presumably 1NT-2C-2D-4C is Gerber), while over 1NT-2C-2maj a bid of the other major is a slam try agreeing opener’s major. BWS is silent on your sequence, but by implication I would say since you can agree the major in a GF auction, 4NT is natural, while 4min is a splinter. I think that’s the sensible way to play it, but you need the GF bid available to you to make it all work.

How do you set trump Paul so you can use keycard? Yes, I do play methods with more eperienced partners to show a fit and slam interest but Kathie and I play barebones standard.

While I would rather like to use 4NT for a general slam try, I am not all that happy with 5H as the way to make a slam try in hearts and I think most stuents would not want to bid a slam without Blackwood. Maybe it is more useful to use 4NT as Blackwood agreeing hearts and give up 4NT as quantitative.

By far the easiest method for students to learn is to use Gerber in ANY auction that started with a notrump opening. So even when Stayman or a transfer has been used a jump to 4C is ace-asking.

Then 4NT in an auction that started with a notrump opening is always quantitative and Blackwood is only used in suit contract auctions.

see:

http://web2.acbl.org/documentLibrary/teachers/ModernNTteacherManual.pdf

Please keep it simple for intermediate students 🙂