A splinter is:
- a double jump shift by opener's partner, or
- a jump shift by opener following a single raise of opener's suit.
For example, 1♥ - 4♣ is a splinter by opener's partner. 1♦ - 1♠ - 4♥ is a splinter by opener.
If partner splintered, alert the bid.
A splinter shows support, a void or small singleton in the splinter suit, and game-forcing strength with slam interest.
A splinter raise of a major shows at least 4-card support. Thus, in the sequence 1♥ - 4♣, at least a 9-card heart fit exists, and opener's partner has a void or small singleton in clubs. In the sequence 1♦ - 1♠ - 4♥, opener shows exactly 4 spades and a void or small singleton in hearts. (With 5 spades, they would have opened spades rather than a minor).
A splinter raise of a minor shows at least 5-card support.
Evaluate your hand carefully before responding.