[Swammerdam]

I'm sure these questions have been answered, but it might be nice to have the answers all in one place.

New Suit by Responder is Forcing is a good general principle, but what are the exceptions?

• Passed hand cannot force- With great strength for a passed hand, I might jump shift, but even that is non-forcing I think.
  
• New suit when opener has limited himself with 1NT rebid is non-forcing (unless it is reverse??) - I would Jump to force.
  
• But if opener has limited himself by rebidding his suit, a new suit IS forcing - Right?
  
• Failure to Redouble? - To clarify for partner should I Redouble a t/o Dble with any hand strong enough to make unconditional force?
  
• Failure to Double 1NT? - Similarly, should I Double a 1NT overcall with any very good hand?
  
• Partner opened Weak Two? - In absence of discussion should I assume "RONF" or "2NT only Force"?
  
• High Level Competition? - Yesterday I bid 3♦ after partner opened 1♠ and my RHO overcalled 2♥. Partner then passed which startled me, but perhaps he thought with the bidding so high "table feel" takes precedence over "rules"?
  
• Other?

[DavidKok]

This is a great initiative, but I think it might be difficult to compile a complete list. Your examples are common agreements, though I'm not a fan of some of the rules in there. Some of them have no safe assumptions without prior discussion.
Regarding your last point, 3♦ is definitely forcing.

[pescetom]

DavidKok, on 2025-July-12, 05:05, said:

This is a great initiative, but I think it might be difficult to compile a complete list. Your examples are common agreements, though I'm not a fan of some of the rules in there. Some of them have no safe assumptions without prior discussion.

More in general, I am skeptical of the utility (or even ethicality) of "in absence of agreements?".
Agreements are agreements: try to avoid playing with people who are not capable of discussing these things or are are unwilling to do so, settle for disclosing the lack of agreement (as your regulations allow/impose) when you do.

[bluenikki]

Swammerdam, on 2025-July-12, 04:46, said:

I[*]Failure to Double 1NT? - Similarly, should I Double a 1NT overcall with any very good hand?
[/list]

2NT over 1NT overcall should show game values with extremish distribution.

[awm]

In general there are two cases:

1. Responder's hand has already been limited in some way. There are several possible cases of this:
.. 1a. Responder is already a passed hand.
.. 1b. Responder started with a competitive pass or 1nt response or negative double, then named a new suit later.
.. 1c. Responder failed to make a value-showing double or redouble (many people still play 1/1 new suits as forcing after double though).
2. Opener's hand is extremely limited, normally by a 1nt rebid or a competitive pass.

Some examples that you didn't capture in the original post:

1♠ - Pass - 1NT - Pass;
2♣ - Pass - 2♦/2♥ are non-forcing

1♦ - 1♠ - Dbl - Pass;
2♣ - Pass - 2♥ is non-forcing (arguably not a "new suit" I suppose)

1♣ - 1♠ - Dbl - Pass;
2♣ - Pass - 2♦ is non-forcing (strong hands with 4♥ and 5+♦ start with 2♦)

1♦ - 2♠ - Pass - Pass;
Dbl - Pass - 3♣/3♥ are non-forcing

1♦ - 1♠ - Pass - 2♠;
Pass - Pass - 3♣ is non-forcing

1♦ - Pass - 1♥ - 1♠;
Pass - Pass - 2♣ is non-forcing (opener's pass is rather like a 1nt rebid)

1♦ - Pass - 1♥ - 1♠;
Pass - 2♠ - 3♣ is more controversial but I think the standard is non-forcing