[mikl_plkcc]

mike777, on 2025-February-22, 11:38, said:

It is NOT a support double, more akin to a responsive double if anything...

Doubles are fun to use. Stop thinking of them as penalty doubles and a whole world of bridge bidding opens up..smile.
Start thinking of doubles as
1. Showing unbid suits
2. Partial support for pards suit
3, asking pard to bid 3NT with a stopper
4, competitive only, pard bid something..
5, pard I have values, but no perfect bid
6, etc

The higher the level, a bit more they lean towards penalty, each level,, but only a bit more..

How do you penalize?
That is a whole other chapter or book..

Doubles are fun, use them more often, especially on tough bidding hands

Enjoyable!

What is the different between support double and responsive double? I think all of them are takeout doubles because all of them are a request for partner to choose an suit.

For example:
(1♥) - X - (2♥) - X is a takeout double. Both partners are short in ♥.

1♦ - (1♥) - X - (2♥) - X is also a takeout double.
The opener has shown that he does not have:

• 6 ♦
  
• 4 ♠
  
• 5 ♦ and 4 ♣

as the opener would have bid holding any of the above. So the inference is that opener has at most 5 ♦, 3 ♣ and 3 ♠, but equally opener may have 5 ♦, 3 ♣, 3 ♥ and 2 ♠ wanting to show extras, lacking a ♥ stopper to bid 2NT. It requests the responder to pick a preference.