[awm]

My teammates were initially using 2nt as a three card raise; I’m not sure the details. Perhaps it’s a three card suit plus a long side suit and opener typically bids 3♣ with four-only major unless very strong/shapely? It’s also possible they changed this further, it’s been a few years.

[DavidKok]

Thank you, do you know if this was a canapé system (1M showing 4 or 6+ almost always) or a majors-first system (1M showing 4+, possibly a longer minor)? The relative merit of raising on three is very different between the two approaches, and one that I've been aiming to design the system around.

[awm]

DavidKok, on 2023-November-26, 14:44, said:

Thank you, do you know if this was a canapé system (1M showing 4 or 6+ almost always) or a majors-first system (1M showing 4+, possibly a longer minor)? The relative merit of raising on three is very different between the two approaches, and one that I've been aiming to design the system around.

Here is their ACBL card. And here is their system notes.

Personally I am not a huge fan of their system, but of course your mileage may vary.

[DavidKok]

Thank you, I ran into the Caroline Club before and learned a lot from those system notes. I'll revisit their competitive agreements in particular, as I've forgotten them somewhere along the way.

Edit: I've looked at the openings again, this system is much closer to SCUM as their 1M openings are only balanced with 5M332 13-15 (depending on vulnerability). This simplifies their competitive decisions after the 1M openings (and makes raising on 3 often correct at the 2-level, as even if partner has only a four card suit we know partner is unbalanced) but makes 1♦ more vulnerable. They put almost all opening hands with a 5cM in 2-level openings.
My suggestion is very similar to their insinuating doubles, except I just call them takeout doubles. The exact split of when to use forcing new bids and when to use negative free bids is interesting and something that I might wish to give more thought. Generally I don't love NFB's though.