[123ekim]

bidding goes

east-pass south-one club west-double north-one notrump
east- double

what the heck does east's double mean?

[peachy]

I don't think this is a system-specific bidding problem [2/1 or SAYC etc].
East's Dbl means East has some values but no five-card suit to bid. With both majors and some values, East would likely bid 2C. Being a passed hand, the values are limited whether he doubled or bid 2C. West, the doubler, can do with this information what he thinks is best.

[Jlall]

pen

[skjaeran]

It's a penalty double.

[helene_t]

In general, dbl of notrumps is penalty. The main reason for this is that if we have the balance of power, we are generally happy to defend a doubled notrump contract, whether we have a fit or not. The same is not true for suit contracts: if we have a fit (so opps likely also have a fit), we are generally not happy defending at a low level, so we should not opt for defending unless we seem not to have a fit.

(1banana)-pass-(1NT)-double*
is an exception, and many partnerships also play
(1banana)-1orange-(1NT)-double*
as take-out, but otherwise, assume dbl of notrumps just shows points and that it is a strong indication of defending.