2D

The ♦2 opener is like our ♣2 opener but weaker. The nominal range is 9 to 12 HCP, though some 12-counts are too strong for it and some good 8-counts get upgraded into it. The response structure mirrors ♣2, with most NF bids shifted up about 1 HCP.

Responses to 2D

2♦

2♥	Artificial asking bid, promising Inv+.
2♠	NF constructive, usually about 8-12 HCP, 5+ ♠.
2NT	NF constructive in ♣ or ♥. 3C is pass or correct; 3D suggests no interest in ♣ and says nothing about ♥.
3♣	Puppet to 3D, showing either a weak raise in ♦ (most common) or a GF 5+/5+ hand without ♦.
3♦	Constructive up to a mild invite, usually around 9-12.
3♥ / 3♠	Natural, 6+ card suit, GF.
3NT	To play.
4♣	RKC for ♦.
4♦	Preemptive.
4♥ / 4♠	To play.

After the 2H asking bid

Opener answers the artificial ♥2 ask as follows.

2♦ – 2♥

2♠	4 cards in either major. 2NT asks: ♥ min / ♠ min / ♥ max / ♠ max.
2NT	Maximum, interest in declaring notrump. Balanced or 6331 with a stiff king.
3♣	Maximum, no 4-card major, unbalanced or unsuitable for notrump.
3♦	Minimum, no 4-card major.
Other	Higher bids are undefined.

After ♦2 - ♥2 - ♣3, a further ♥3 by responder asks for shortness, showing it up the line (clubs, diamonds, hearts, spades).