[PhilG007]

An opening bid of 4NT is a rare bird. In most bidding systems,it calls on partner to cue bid any Aces he holds
by bidding its suit. However,I have noticed,particularly in BBO tournaments that 4NT has been opened and on
asking for an explanation got the reply "Blackwood for Aces" To me this is perplexing. I was always under the
impression that Blackwood operated once a trump suit had been agreed,either directly or by inference.
To do so without any suit being mentioned at all is,to me just bizarre. Am I missing something here(?)

[nige1]

PhilG007, on 2019-November-16, 07:51, said:

An opening bid of 4NT is a rare bird. In most bidding systems,it calls on partner to cue bid any Aces he holds
by bidding its suit. However,I have noticed,particularly in BBO tournaments that 4NT has been opened and on
asking for an explanation got the reply "Blackwood for Aces" To me this is perplexing. I was always under the
impression that Blackwood operated once a trump suit had been agreed,either directly or by inference.
To do so without any suit being mentioned at all is,to me just bizarre. Am I missing something here(?)

IMO, the Acol opening 4N ask is flawed (If you must find about specific aces, it's probably better to deny than show them). Hence almost any other meaning is an improvement. e.g. a slam try in a minor, both minors, a balanced power-house, or ordinary Blackwood.

[gordontd]

nige1, on 2019-November-16, 08:05, said:

IMO, the Acol opening 4N ask is flawed (If you must find about specific aces, it's probably better to deny than show them). Hence almost any other meaning is an improvement. e.g. a slam try in a minor, both minors, a balanced power-house, or ordinary Blackwood.

Good to point out that it's an Acol bid and is not part of "most bidding systems" as claimed by the original poster.

[pescetom]

nige1, on 2019-November-16, 08:05, said:

IMO, the Acol opening 4N ask is flawed (If you must find about specific aces, it's probably better to deny than show them). Hence almost any other meaning is an improvement. e.g. a slam try in a minor, both minors, a balanced power-house, or ordinary Blackwood.

My variant of the Acol 4N ask can show 2 aces and not just a specific ace, also has developments to explore specific kings when possible for that matter. I'm dubious about slam try in a minor or a balanced power-house (can show both clearly after 2♣), but both minors with moderate slam interest is worthy of thought (and such a strong preempt) I agree.

[kreivi68]

If you play Namyats convention or similar, you can add one-suited major blockbusters to it. I wrote an article about the idea to The Bridge World (July 2016) called SuperNamyats.
So 4C/D opening would be either strong preempt or very strong one-suiter with heart/spade suit. After responder signs off in 4H/S opener continues with strong variant:
4NT is key-card ask, new suit is Exclusion Blackwood and jump to 6C/D shows strong two-suiter missing only one honor in either suit. This leaves 4NT opening for more
useful purposes.

[pescetom]

I was asked to describe my version of 4NT Specific Ace Ask and this seemed to be the most pertinent thread.

Although reading more closely I see nobody described the original Acol version, which is that when a player opens with 4NT, partner responds based on which specific ace they hold:
5♣ = no aces
5♦ = Ace of Diamonds
5♥ = Ace of Hearts
5♠ = Ace of Spades
5NT = two aces
6♣ = Ace of Clubs.
Simple and sweet, although not very powerful and with the awkward quirk that Ace of Clubs forces to slam (some play suit-above responses to solve that, but the risk of a misunderstanding is notable).

I started by eliminating the clubs jump. Then I added the ability to ask for Specific King(s) after Specific Ace(s) and to be able to pinpoint any pair (it's frustrating to learn that Responder has two unidentifiable Aces when you hold one and need another specific one - or two - for grand).

So when a player opens with 4NT asking for specific ace(s), partner now responds:
5♣ = no aces or Ace of Clubs (5♦ asks: 5♥ = no aces, 5♠ = Ace of Clubs)
5♦ = Ace of Diamonds
5♥ = Ace of Hearts
5♠ = Ace of Spades
5NT = two aces of same colour (red or black)
6♣ = two aces of same rank (major or minor)
6♦ = two aces of same order (pointed or rounded)
6♥ = three aces.

Any rebid by Opener is signoff, except 5NT over 5♦/♥/♠ (or over 5♣ - 5♦ - 5♥/♠) which asks for specific king(s).
The response scheme to 5NT asking for specific king(s) is the same as that for specific aces:
6♣ = no kings or King of Clubs (6♦ asks: 6♥ = no kings, 6♠ = King of Clubs)
6♦ = King of Diamonds
6♥ = King of Hearts
6♠ = King of Spades
6NT = two kings of same colour
7♣ = two kings of same rank
7♦ = two kings of same order
7♥ = three kings.

French and Italian players will find the scheme easier to remember as colour/rank/order is borrowed from an Albarran strong 2♣ opening.

[jillybean]

Thanks. I like simple so the ACOL version with your extension to ask for club Ace sounds about right.
Hopefully you are not getting to the 5nt response too often, what type of hands do you need to open 4nt?

[pescetom]

jillybean, on 2026-June-26, 09:12, said:

Thanks. I like simple so the ACOL version with your extension to ask for club Ace sounds about right.
Hopefully you are not getting to the 5nt response too often, what type of hands do you need to open 4nt?

4NT is already very low frequency and Responder only has the desired ace one time in three (it seems like less). But when it does happen then asking for kings can sometimes make the difference (one might even bid 4NT with 4 aces just to get there). And the kings information pretty much has to be specific, "any two kings" may mean deciding grand on 67% rather than 100% or 0%. As with any ask, one should think hard before making it if there is any possible response that may force us too high.

OTOH, I've never had a 3 aces response

[TMorris]

The opening bid comes up so rarely you want simple responses you will remember. I have no confidence 2 of my 3 regular pratners will remember the opening for example which for me has come up once in around 30 years.

You want a big two suiter with solid suits one of more missing an ace IMO to bid it.

[pescetom]

TMorris, on 2026-June-26, 10:46, said:

The opening bid comes up so rarely you want simple responses you will remember. I have no confidence 2 of my 3 regular pratners will remember the opening for example which for me has come up once in around 30 years.

I would say about twice a year, but still not at all frequent. Obviously you want responses you will remember, simple or not.
As I said, the CRO logic is familiar to French and Italians (or students of bridge history).
I find that a similar quirk actually makes a convention easier to remember (think showing the wrong major in Puppet Stayman), but probably that's just me.
You can certainly survive without it.

TMorris, on 2026-June-26, 10:46, said:

You want a big two suiter with solid suits one of more missing an ace IMO to bid it.

That is one of several possible hands. The essence IMO is that you have very few losers and only need to know specific Aces and/or Kings.