Multi or Multi 2 diamonds is contract bridge convention whereby the opening bid of 2♦ shows multiple types of hands, which always includes a weak two bid in either major suit, while the additional meaning can be either a balanced hand in 18-20 high card points range, or a 20-22 three suiter.

Although it's technically a brown sticker convention (since no long suit is initially known), its popularity and availability of defenses persuaded World Bridge Federation to allow its usage on tournaments of lesser ratings. It is described in WBF Convention Booklet.

Description

An opening bid of 2♦ shows one of three types :

1. Weak two in a major suit (6-11 HCP)
2. A strong balanced hand of a defined range
3. Strong three-suited hand

The first response assumes that opener has a weak two in a major.

• 2♥: Pass or correct
• 2♠: Pass or correct to 3♥ implies interest in game if the opener has hearts;
• 2NT: Forcing, asking opener to clarify his hand.

Opener's rebids:

• With type (1):
  • Over 2♥: pass or bid 2S
  • Over 2♥: with hearts, bid 3H.
  • Over 2NT:
    • bid 3♣ to show hearts, upper range;
    • 3♦ to show spades, upper range;
    • 3♥ or 3♠ with lower range.
• With type (2):
  • rebid in notrumps at minimum level
• Other rebids show type (3) and should be specified on the Convention card.