The bidding has started, but the first 2 or 3 players (including yourself) have passed. Fortunately your Partner (sitting in 3rd or 4th position) opens with 1♥. You have trump support and a maximum pass points ( . . . . points) and convey this happy news with a standard . . . . . . . . . . . . . . . . . Unfortunately Partner (enticed by his long major suit) made a rather light opening with a mere 11 points and the contract goes one down.
What to do ?   Should Partner have passed in the first place ?   Of course not, because the . . . . . . . . . Convention (amongst some also known as . . . . . . . . . . . ) provides the perfect solution.

After an Opening of . . . . . or . . . . . . . by a player in . . . . . . . . . position, his Partner (who has previously passed) responds with . . . . . . when he has . . . . . . and . . . . . . points.
Replies by the Opener are :

After Opener's weak reply of . . . . . Responder will usually sign on in . . . . . . . . . .

After an Overcall or Double by the Opposition, Responder's 2♣ remains . . . . . .

In a case where Responder holds a genuine long . . . . . . . suit but no support for . . . . . . . , he bids . . . . . first, then rebids . . . . . at his next turn.

After Enemy interference a . . . . . by Opener shows a minimum (. . . . . pts). All his other bids show . . . . points.

The Crowhurst 2♣ convention is another useful convention which provides the Opener with a chance to describe his hand in greater detail. (This convention is very similar to . . . . . . . . . . . . and . . . . . . . . . . . )

After any two suit bids at the . . . level followed by a rebid by the Opener of . . . . (showing . . . . . . points) a rebid by the Responder of 2♣ is . . . . . . . . and . . . . . . . . . . . It shows . . . . . points and an interest in . . . . . . .

In all above (and similar) cases a rebid of . . . . . . . by the Responder is Crowhurst. Any other new suit bid at the . . . level by Responder shows a . . . . . . . . . hand, after which Opener may . . . . . or show a . . . . . . . . .

Here follow some typical examples.

After Responder's Crowhurst . . . . . rebid, Opener has the following order of priorities :

1. show the . . . . . . . . . . . if he holds it.
   This is only relevant when Responder's first bid was . . . . . . , so that Opener was unable to bid his . . . . . . . suit.

2. show . . . . . . . . . for Responder's . . . . suit.

3. show his . . . . . . . . .

4. Show his . . . . . . . . . . . for a possible . . . . . contract.

5. When Opener is unable to bid any of the above, he will rebid . . . . . . . . . . .

Opener will reply at the . . . . . level with a minimum . . . . . . points.

Opener will reply at the . . . . level with a maximum . . . . . . points.

After Enemy interference a . . . . . . . by Openers shows a minimum (. . . . . . ). All his other bids show . . . . . points.

Here follow some typical examples.