[kortkungen]

With a previous partner we played: a new suit at the 4 level (or 3♠) that appears non-natural or unnecessary, confirms last suit of partner and is a control trying for slem. This has worked really well, and rarely caused confusion or conflict.
I guess this happened mostly after NT or 2-openings when there is less bidding space and/or no 4th suit available.
Eg this morning after a multi 2♦ opening by partner:
2♦ - 2NT - 3♣
3♣ shows 6-8 pnt with 6-card ♥. I had a beautiful 21 pnt and 3 hearts, but no control in ♦. With my previous partner I would have bid 4♣ (confirming ♥ trump and ♣ control), and he would show diamond control.

Want to introduce this method to partner, but I have no idea what's it called, and where I can find a good explanation. We kind of invented it ourselves I think? Searching for it here did not help.
Does anyone recognize this?

[DavidKok]

I'm somewhat familiar with "4♣ is a slam-oriented raise of partner's suit", which serves a similar function. The idea is that hands with a long and strong minor suit tend to want to play in 3NT, so using 4m to describe these hands is a poor idea on most auctions, and it's arguably about as good to leave them idle (and better still to use them for cooperative slam tries). Unfortunately I don't have a clear list of rules on when it applies. If someone has an explanation of the method I'd love to read more about it.

[kortkungen]

DavidKok, on 2023-August-16, 05:39, said:

I'm somewhat familiar with "4♣ is a slam-oriented raise of partner's suit", which serves a similar function. The idea is that hands with a long and strong minor suit tend to want to play in 3NT, so using 4m to describe these hands is a poor idea on most auctions, and it's arguably about as good to leave them idle (and better still to use them for cooperative slam tries). Unfortunately I don't have a clear list of rules on when it applies. If someone has an explanation of the method I'd love to read more about it.

Yes it's similar, except that I also show a control. A 4♦ bid in that situation would have the same purpose of establishing trump, but denies a club control.

[Stephen Tu]

This kind of thing is called an "advance cue bid" in the bridge literature, control showing before explicit suit agreement (the cue bid agrees the suit by inference). It's somewhat standard among better players. It should generally apply when one partner has shown a solid one suiter, or one partner has shown a one suiter and the other has shown balanced hand previously, had opportunity to introduce the cue bid suit naturally earlier but declined to do so. It should arguably not apply when it's the first chance to show the suit naturally and it's reasonably likely one would want to maybe play in that strain.