[cherdano]

For this discussion, assume that opponents have are making an artificial bid in an unbid suit, and neither partner nor I have made a bid other than pass so far. Thinks of Transfer, Bergen raise, drury, short suit game try, mini-splinter, splinter, negative or waiting 2♦ or 1♦, ogust etc.
Often they may have found, or are likely to have a fit.
Useful meanings of a double could include

• take-out
  
• card-showing, possibly indicating desire to double them
  
• suggesting a sacrifice in the bid suit
  
• purely lead directional.

Obviously you cannot discuss all possible situations, so you need some general rules. What agreements do you have in your favorite partnership(s) to decide which meaning is applicable? Which situations lead to misunderstandings most often and should be discussed with partner?

Arend

[Rebound]

I gerenerally play that without prior agreement, a double of any artificial bid shows the suit bid. I'm sure others here will describe more advanced treatments but it works for me.

The context will often indicate whether the double is high card-showing or based on length. If there is a rule one can apply to that I would be interested in hearing it.

However, see The_Hog's new thread, http://bridgebase.lunarpages.com/~bridge2/...?showtopic=4939

for some different ideas.

[han]

In all of the situations you mention I have specific agreements with my regular partners, like many players probably do:

transfers: lead director. (if at the two level, invites partner to compete in the suit)
Bergen Raise, Drury: take out of the major.
ssgt, (mini-) splinter excl-RKC: ask for a lead in the highest unbid suit.
negative or waiting 1D/2D: exactly as over 1C/2C, for me the majors.

You can see some guilines here:

1) The higher their bid, the more likely the double is lead-directing.

2) If they use an artificial bid to establish a big fit at a low level, then a double is take-out.

3) Over a splinter-like bid, a double is lead directing, but not for the splinter-suit (that would be silly) but for the highest unbid suit (this is random, I have heard people claim that lowest bid suit is better ).

These guidelines would probably do the job for most of the artificial bids you encounter. Oh, you also need some agreement for 2-suited overcalls (like michaels or UNT).