[gwnn]

My knowledge of jump shift auctions is chaotic and proportional to absolute temperature.

1♦-1♥
2♠-3♦ (2NT would be artificial and weak)
3NT-4NT

I assume this is natural and quantitative.

What's the difference between the hands contained here and in 4♦?

What if responder really really wants to RKC (I heard the expert expression "this is a hand that wants to ask/wants to show keycards)?

[hrothgar]

Redwood / Minorwood etc. is one popular approach

[jdonn]

3♦ was just a preference, there might not even be a diamond fit. That's the difference.

Of course if you want to bid keycard the easiest way is probably to bid 4♦ over 3NT, then 4NT. Partner will cuebid a major for you, and even in the <1% of the time that he can't or doesn't, that fact alone will probably give you the info you need.

[Cascade]

4♦ is a hand that wants to strongly suggest diamonds (at least temporarily).

4NT is general strength.

We have the agreement that after 4♦ partner can immediately return to 4NT natural (and discouraging for slam purposes) or cue.

[Echognome]

I would play that 4NT is quantitative.

4♦ would be slam invitational in diamonds and, as Wayne, the only regressive bid available is 4NT by opener. In all other sequences, 4NT becomes keycard.

[cyc0002002]

Cascade, on May 26 2009, 03:31 PM, said:

We have the agreement that after 4♦ partner can immediately return to 4NT natural (and discouraging for slam purposes) or cue.

This is quite good when playing MP.

[Cascade]

cyc0002002, on May 27 2009, 02:39 PM, said:

Cascade, on May 26 2009, 03:31 PM, said:

We have the agreement that after 4♦ partner can immediately return to 4NT natural (and discouraging for slam purposes) or cue.

This is quite good when playing MP.

Yes it is also good at IMPs where you often have invitational slam hands where you need some input from partner so you need some uncooperative bid.

I suppose the uncooperative bid could be 5minor.