[lycier]

First double,then bid suit, for this suit, there are many different style explanations.

-Hand-1

---

4♦ says " 5-♣,5-♥,4+♠,rebiddable ♦,25+TPs".

-Hand-2

---

2♦ says " 5+♦,18-20TPs".

-Hand-3

---

3♦ says " 5-♣,6+♦,5-♥,4+♠,15+TPs ".

-Hand-4

---

4♦ says " 5+♦,17+TPs".
First double then bid suit, there are several different explanations in the such situations.
A bit of mess.

[Stephen Tu]

This is illustrative of the problems in fixing GIB. A human sees the situations as similar, takeout double then bid a new suit. But to a computer, each situation is quite different, one opp vs. both opps bidding first, the level one bids the suit at, whether you are bidding it over partner's response to takeout double, freely in comp over a passing partner, in balancing position or in a live auction. So each triggers different rules, which can have potentially different explanations, and it's difficult with so many rules to keep them consistent with each other. And we don't necessarily want them the same. I do think bidding at the 4 level should have more length/strength than bidding at the 2 level. And perhaps with two bidding opps you really ought to have both other suits when doubling rather than considering hands too strong to overcall. Or at least stronger minimums when short in the unbid major.