Responses to 1♦
1♦ ---
1♥ : 6+ HCP, 4+♥. With 4-4 majors, bid 1♥.
1♠ : 6+ HCP, 4+♠. With 5-5 majors, bid 1♠.
1NT : 6-10 HCP, balanced.
2♣ : {12+ HCP, GF, ♣ 4+(♣ 4 only when 3-3-3-4)}
2♦ : 10+ HCP, 4+♦ support, forcing to 2NT/3♦.
2♥/♠ : Preemptive, 3-6 HCP, 6+ suit.
2NT : 11-12 HCP, balanced, inv.
3♣ : 10-11HCP, 6+♣.
3♦ : Preemptive raise.
3♥/♠* : 12-15 HCP, Splinter for ♦ fit.
3NT : 13-15HCP, balanced, to play.
Developments After 1♦ - 1♥
1♦ - 1♥;
1♠ : ... (Similar developments as 1♣ opening auctions)
1NT : 12-14 HCP, balanced, denies 4♠ or 3145 shape.
2♣* : Transfer to 2♦. Weak with diamonds, or any inv hand.
2♦* : Artificial, GF.
2♥ : 6+ card suit, weak.
2♠ : Reverse response, GF.
2NT : Forcing transfer to 3♣. After 3♣, Pass = weak clubs, 3♦=5-5+ invite.
3♦ : 5-5+ two-suiter, GF.
3♥ : 6+ card semi-solid suit, GF.
3NT : To play, generally 4-card major.
2♣ : 12-17P, 4+♣.
2♦ : 12-15P, 6+♦.
2♥ : 12-14P, 4-card support.
2♠ : 16+P, reverse, F1.
2NT : 18-19P, balanced.
3♣ : 18+P, second suit, forcing.
3♦ : 15-17P, good 6+♦ suit.
3♥ : 15-17P, 4-card support, inv.
3♠/4♣* : Splinter with ♥ support.
Developments After 1♦ - 1♠
1♦ - 1♠;
1NT : 12-14 HCP, balanced.
2♣* : Transfer to 2♦. Weak with ♦ or any invite.
2♦* : Artificial, GF.
2♥ : 5♠4♥, weak.
2♠ : 6+ card suit, weak.
2NT* : Forcing transfer to 3♣. After 3♣, Pass = weak clubs, 3♦=5-5+ invite.
3♣ : GF, 5+♣, 5+♠.
3♦ : GF, 5+♦, 5+♠.
3♥ : GF, 5+♥, 5+♠.
3♠ : GF, solid suit.
3NT : To play.
2♣ : 12-17 HCP, 5+♦(can be 4 when 1-4-4-4), 4+♣.
2♦ : Weak, to play.
2♥* : 4th Suit Forcing, GF.
2♠ : Weak, to play.
2NT : Inv, can be unbal.
3♣ : 4+♣, inv.
3♦ : 3+ support, inv.
3♥* : Splinter, 13-15 HCP, 4+♣.
3♠ : 6+♠, inv.
2♦ : 12-15 HCP, 6+♦.
2♥ : Reverse, 16+ HCP, 5+♦, 4+♥, F1.
2♠ : 12-14 HCP, 3+ support.
2NT : 18-19 HCP, balanced.
3♣ : 18+ HCP, 5+♦, 4+♣.
3♦ : 15-17 HCP, 6+♦.
3♥* : Splinter, 15-17 HCP, ♠ support, ♥ shortness.
3♠ : 15-17 HCP, 4+ support.
3NT : 18-19 HCP, 4+ support, balanced.
Developments After 1♦ - 1NT
1♦ - 1NT;
2♣ : 12-17 HCP, ♦ 4+, ♣ 4+
2♦ : 12-15 HCP, ♦ 6+ or ♦ 5+, unbalanced
2♥/♠ : reverse, 16+ HCP
2NT : inv, 16-17 unbal
3♣ : 18+ HCP, ♦ 5+, ♣ 4+
3♦ : 15-17 HCP, ♦ 6+
3♥/♠ : 16+ HCP, two suits 6-5+
3NT : 18+ HCP, bal
Developments After 1♦ - 2♣
{
1♦ - 2♣;
2♦ : ♦ 5+, no ♣ fit, does not deny 4M
2♥/♠ : Natural, ♣ 5+, ♥/♠ 4+
2NT : relay, no 4M, no ♦ fit, usually with ♣ 5
3♣ : ♣ 3
3♦ : ♦ 6+
3♥/♠ : showing stoppers
3NT : minimum bal, generally 3-3-5-2
3♣ : ♣ 6+
3♦ : ♦ fit
3♥/♠* : SPL, ♦ 3+ fit
2♥/♠ : ♥/♠ 4+, generally no ♦5. 2♥ does not deny ♠ 4 (can be 4-4-4-1)
2NT : bal, 12-14 HCP, deny 4 card Major
3♣ : ♣ 4+
3♦ : At least semi-solid ♦ 6+, any value, GF
3♥/♠ : SPL, 12-15 HCP
3NT : 18-19 HCP, bal
}