[chakman1]

What does 1N mean in the balancing seat after already opening?
P 1D 1H P
P 1N?

Can opener have a basic hand with H stopper(s) like K9, AQX, KQXXX, XX? It appers partner is marked with some values and has neither 4S nor a H stopper and so can take no action.

OR - does it need to be a big hand as in this second seat scenario?
1C X P 1(another suit)
P 1N

[mycroft]

In modern bridge, partner is marked with nothing unless she has a penalty double of hearts. The overcall took no room away, and actually gave a bid to show 4 vs 5 spades (or cards-and-not-4-spades vs 4 spades, rare agreement). Unless you have that rare agreement, she could have a balanced 7 with no spades and no heart stopper (that would have responded 1NT after 1♦-p), but she would try to raise diamonds then.

Overcaller is "unlimited", and could easily be 18. There are exceptions, but you should assume that you and LHO have 30+ between you, and his cards are over yours. Your 1NT shows a hand too strong to open 1NT - the one that would have rebid 2NT if your partner had bid instead of the opposition.

Note that you are expected to double with any hand that would pass a penalty double of hearts (if that's feasible for partner), or any hand that is comfortable playing partner's suit, whatever it is.

The second scenario is even bigger, because the natural 1NT overcall should be stronger (by almost a point) than a strong 1NT opening. So, 19-20. Here partner could be on nothing because she had to bid.

And now I'm going to be corrected by the people who spend the time I spend directing, playing.

[pigpenz]

agree with mycroft on this, its a pass no source of tricks if partner is broke
and most likely partner has no hand and 5 crappy spades.

NOTE: and it might also depend on what my 13th card is as I am 2352!
also if partner had weakish hand with 4 diamonds he could bid 2♦.
the lack of negative double eliminates alot of hands partner could have.
so it looks like let them play 1♥ if i had Kxx♠ might make spades playable but
chances are you could end up at 2 level

[mikeh]

A reopening 1N shows 18-19 hcp.

Btw, partner is not ‘marked with some values’, although he doesn’t deny values after say 1C (1S) P (P) and you hold something like Kx AQx xxx KQxxx.

Lho could have a big hand ill-suited, in his view, for double then spades, and Rho may have a decent hand with short spades and no club stopper and no suit.

Say AQJxx x Axxx Axx opposite xx KJxx KQxx xxx