[pigpenz]

am curious as to what people use in response to 5NT??
Like say a new suit below the suit at 7 level as a King etc
or 6NT showing a void. etc

[mikeh]

The method I use depends on the suit that is agreed as trump, subject to the caveat that very few 5N bids are GSF anymore: choice of slams is the default meaning in most sequences.

Having ♠ as trump offers the most flexibility because we have the entire 6 level plus 7♣ as responses (all GSF methods should/do use 7♣ as the acceptance of the GSF to maximize flexibility)

With ♠ as trump:

6♣ A or K with extra length (usually compensates for the missing Q)
6♦ A or K without extra length
6♥ Q, no A or K
6♠ no top honours at all
7♣ 2/3 top honours

If we agree ♥, we drop the Q response: 6♥ is no A or K and is silent on the Q
If we agree ♦, then we drop the 6♦ A or K without extra length: we now have only 3 steps: A or K with extra length is 6♣, 2/3 tops is 7 and 6♦ is anything else

If we agree ♣ we only have 2 possible responses: 6♣ no 2/3 tops and 7♣ yes 2/3 tops.

While I have played this for many years, it has NEVER come up (well, it did once, but I have AQ so bid 7♣).

These days, with 5N pick a slam and RKCB the occasions for GSF are limited and I would not recommend anything complex for any but frequent partners.

[awm]

Sam and I generally play step responses. In principle:

6♣ = no top honor
6♦ = one top honor
6♥ = two top honors
6♠ = three top honors

However, these bids will be compressed if the trump suit is a minor. So we use 6♣ = "my trump holding will be disappointing given the earlier auction" and go from there.

[pclayton]

I would think most play that 7 shows 2 of the top 3 and 6 trump show the weakest. Between 5N and 6 of trump the responses are gradiants between these two.

[kenrexford]

GSF is almost the least useful of conventions these days. So, for the one hand in a trillion where you need it, let us develop really obscure and esoteric responses.

GSF asks for trump suit quality. Aces are obviously critical. Kings are usually critical, and Queens are sometimes critical. Trump length might "replace" an honor.

So, perhaps:

Six of the suit = no help; neither unexpected trump length nor trump honors.

6♥ (spades are trumps) = Extra trump length, but no honor.

6♦ (spades are trumps = The king or Queen, no extra length (6♥ invites if the King is held)

6♣ (spades are trumps) = The Ace, King, or Queen, with extra trump length (6♦ asks for clarification; 6♥=Q; 6♠=K; 6NT=A)

With two top honors, bid 6NT with AQ/KQ; 7♣ with AK. With all three, bid 7♦.

With the Ace, but no extra trump length, bid 6♣. When partner asks (6♦), bid 6♥. If partner has the Queen, he will know what you have. If partner has K-empty, he may bid 6♠, in which case you will convert to 6NT.

If hearts are trumps, skip the "extra trump length but no honor" option. You lose the asking bid after 6♦. After 6♣, 6♦ still asks, with the same answers, except that you cannot bid 5NT with K-empty.

If diamonds are trumps, 6♦ shows the minimum so far, 6♣ +1 honor from expectation, and 6♥/♠/NT shows two honors, identifying the missing one by steps.

If clubs are trumps, pass 5NT.

[1eyedjack]

Similar to the above. I tend to play that 5 of the denomination above the agreed trump suit is the GSF, ie 5D if Clubs are trumps, 5H if D are trumps and so on. Have to be a bit careful where there are more than one potential trump suits.

Then
Step 1 = at most the Jack
Step 2 = A or K, no Q, no extra length
Step 3 = A or K, no Q, one extra
Step 4 = A or K, no Q, 2+ extra length
Steps 5+ = 2+ top honours, descriptive (possibly better trump location or NT)

After Step 1, next step is relay confirming possession of both AK, then
Step 1 = no extra length
Step 2 = 1 extra
Step 3+ = 2+ extra

We assume that you have a minimum of an 8 card fit to start with.
With anything less than a 10 card fit, 3 of top 3 honours are required and sufficient
With a 10 card fit (but no less), it is desirable to be in grand slam with both AK regardless of Q.
With a 12 card fit (but no less), it is desirable to be in grand slam with the Ace regardless of K or Q. But these continuations are not capable of catering for the 12 card fit. With anything less than a 12 card fit the Ace and King effectively rank equally, as missing either of those cards is sufficient to stay out of the grand.

There is a case for being in the grand when missing just the King, and opposition bidding makes the finesse a heavy favourite, but again this mechanism will not find it.

It seems the GSF still has some life in it. Hackett and Hackett recently used it in a Matchpointed event to good effect:
Holding
♠KQxxxxx
♥QJ
♦AK
♣xx

1♠ - (4♦) - 5N - (P)
7N

for a great MP score against those in 7♠. Partner had the ♥K to go with the missing Aces, and of course, ♦ void.

[ArcLight]

Since the Grand Slam Force is less valuable today because of Roman Keycard Blackwood (where you can also find out about the trump quality) I would be careful interpreting 5NT because pard may mean it for Pick a Slam.
You will end up in an "adventurous" 7 level contract!