[pilun]

In the modern style, a 2♣ opening shows six.

In response, 2M is often played as "constructive", so around 9-12 points and a 6-carder or chunky 5-carder.
Stronger responding hands either jump or start with 2♦ as some sort of relay, say 13+.
Your numbers may vary.

Consider opener's options.
If a 4-card major is permitted, then
2♣ - 2♥ - 2♠ is presumably natural. Likewise
2♣ - 2♠ - 3♥, though that would be rare.

When should opener pass 2M?
What does 2NT show?
When to bid 3♣?
Does opener always raise with three trumps?

Presumably a minimum with a doubleton in partner's suit will pass.
What about the same with a singleton?
Does that hand bid 3♣, or does 3♣ show a chunky suit? So

♠x ♥Axx ♦Qxx ♣KJxxxx

Pass or 3♣? What is your style?

What does opener do with a stiff major and a maximum? Still "sign-off" in 3♣?
Or can 2NT show that hand? Say 1-3-3-6 14-15, discouraging a retreat.
Or does 2NT show a good hand with tolerance, so responder can bid 3M or 4M?

Does opener always raise with three trumps, jumping with a maximum?
Is there then a way to show a good raise to 3M?

[foobar]

IMO, it's best to play 2M as forcing for one round but YMMV.

[steve2005]

You should freely raise major with support

[benlessard]

I like to play
2M inv with 4/5 (partner can only pass with 3) and paradox 2D.
2C--2D--??

2H= I refuse facing 6H inv
2S= I accept H but refuse spades
2NT= min but accept both M
anytime we are inv and opener is min we stop at 2 level or in 3C. Allow you to make aggressive invite so we dont miss games. I do play 2C can be 5C+4M and other than huge memory strain we have no problems.

[pilun]

foobar, on 2023-July-06, 17:46, said:

IMO, it's best to play 2M as forcing for one round but YMMV.

Atul,

That method has merit.

However, it puts opener under even more pressure, particularly on hands lacking support.

What to do on hands with tolerance vs those with a singleton (or void)?
What to do with minimums vs maximums?

How do you use the two bids available for those four hands?
Or do you have to go past the barrier with some maximums?

[foobar]

pilun, on 2023-July-07, 10:02, said:

Atul,

That method has merit.

However, it puts opener under even more pressure, particularly on hands lacking support.

What to do on hands with tolerance vs those with a singleton (or void)?
What to do with minimums vs maximums?

How do you use the two bids available for those four hands?
Or do you have to go past the barrier with some maximums?

Basically, since 2C - 3M as GF with 6+, 2M is the fairly narrow "constructive F1", opener can retreat to 2N / 3C with min, or advance past with a maximum. Frankly, given the relative rarity of the opening, it's probably not worth investing too much thought into it.

[pilun]

foobar, on 2023-July-07, 10:52, said:

Basically, since 2C - 3M as GF with 6+, 2M is the fairly narrow "constructive F1", opener can retreat to 2N / 3C with min, or advance past with a maximum. Frankly, given the relative rarity of the opening, it's probably not worth investing too much thought into it.

Simple enough on most hands that aren't going to raise is
2NT with maximums, 3♣ with minimums.

An alternative is to only bid 3♣ with chunky clubs and a stiff spade, when maximums have a guess to make.