Bid this

[wackojack]

At white, you have:
  AJ87542
  9
  KQ7
  104
LHO passes and partner opens 1 , you respond 1 , partner rebids 3 .  This I take as game forcing and so I rebid 3  taking it slowly in the game forcing situation.  Partner now raises to 4  . I still have lots of unadvertised strength and it seemed that there was no alternative to Blackwood 4N.  (comments?) Partner responded 5 showing 3 keycards. 
1    1
3     3
4    4NT
5    ?

Would you now go straight to 6 ?  Or try 5 which I believe is a trump Queen ask?  If partner denies the Q and just bids 5 would you pass or continue to 6  ? I went on to 6  on the basis that if partner had a doubleton spade without the queen, the slam would still be slightly better than evens and partner might even have 3 spades. 

Partner's hand was disappointing:

  K3
  AK764
  A8
  QJ96

The 4  was led but I still went off when RHO had  Q109 and I went with the odds and played for the drop. 

I appreciate that with a good 17 a rebid of 2  can sometimes result in a missed game.  Nevertheless I believe that a rebid of 2NT (18-19) fits the bill much better.  I do notice that a 5422 hand does seem to draw partners into showing their 2nd suit.  Now:
1    1
2NT    ?

Am I too good for 4 , and would 3 be a sign off?  What would 3  be taken as?  A Wolf sign-off?  (3 is a relay to 3  and then 3 is a sign-off)  Then 3  would be forcing.  So we get to;
1    1
2NT    3
?
Surely opener must next make the courtesy cue bid of 4  .  Now if you play that this bid denies 1st or 2nd round control in clubs then we sign off in 4  safely. 

What if you are not playing the Wolff sign-off.  What would be sensible?

 
 





   

[jcreech]

Once partner jump shifts, it is hard to stay out of this slam.  When I played it, partner only bid 2 , so I was able to jump to 3 as an invitation.  Partner accepted, but did not go overboard, so I got to play it in game.  My opps also did not lead clubs, so I was able to shag one early, but was disappointed in the spade layout as well. 

At least I didn't have your slam making to sour the result - which was dismal given that you can't make five and some should have been there going down with you, but someone foolishly left in a double of 2 to help keep the slightly under bid spade games from getting too large of a score.

[Masse24]

It's not worth a jump-shift.

I would choose to rebid 2 , and it would be my preference, but I am not married to it. Then, an invitational jump to 3 is also correct (as Jim opted for).

I think rebidding 2NT is also fine.

With the auction as it went (and having the luxury of seeing both hands), after partner bid 4 , maybe 5 instead of 4NT? Clearly this denies a control, so partner, missing a control as well, would sign off in 5 . Small consolation since you would likely still play the trump suit as you did.

[Added] In the auction as it went, you are already in a GF, so after your 3 rebid, what would 4 be by your partner? Surely it agrees spades? Does it show two? Three? A control? What, then, does the failure to bid 4 (instead just bidding game with 4 ) indicate? I dunno. Just throwing it out there for discussion.

[wackojack]

It's not worth a jump-shift.

I would choose to rebid 2 , and it would be my preference, but I am not married to it. Then, an invitational jump to 3 is also correct (as Jim opted for).

I think rebidding 2NT is also fine.

With the auction as it went (and having the luxury of seeing both hands), after partner bid 4 , maybe 5 instead of 4NT? Clearly this denies a control, so partner, missing a control as well, would sign off in 5 . Small consolation since you would likely still play the trump suit as you did.

[Added] In the auction as it went, you are already in a GF, so after your 3 rebid, what would 4 be by your partner? Surely it agrees spades? Does it show two? Three? A control? What,
then, does the failure to bid 4 (instead just bidding game with 4 ) indicate? I dunno. Just throwing it out there for discussion.

Yes 3 cannot be a natural 4 card suit showing 0544 distribution because we cannot be looking for a 4-4  fit since I could have bid 4  myself.  OR COULD IT?  Give partner 20HCP with 0544 distribution and what can she otherwise bid? 

Any comments about the Wolff sign-off after a 1 -1 -2NT auction?  Does this give you anything better than 3 check-back?  Unfortunately it gives room for completely opposite interpretation.  Playing Wolff 2NT -3 is forcing and could be a slam try.  Not playing Wolff 2NT-3 I assume is not forcing because if you want to force you go through 3 check-back.

What is most common interpretation of 3  in the USA after 1 -1 - 2NT?   

[kenberg]

I think there is something to be said for playing that after  1 - 1 - 2NT all bids are natural and forcing. This is especially true if1 - 2 is a weak jump shift since then it is not all that likely that after 1 - 1 - 2NT you will want to sign off in 3 . After 1 - 1 - 2NT it is reasonably possible that you belong in 5m or 6m and having 3 m as natural and forcing can help figure this out.

For example, suppose opener has the shape he has in this example, 2=5=2=4. Responder might be 4=1=3=5, with too little strength to bid 2 over 1 . Bidding 3 over 2NT sounds good.

But you asked what is common and I doubt that natural is common. 
Probably considered weird.
I assume NMF when I play.