Partner has opened 1♣ or 1♦. Choose your response:

• 0–5 HCP, no fit → Pass
• Fit (4+ cards), add shortage points: void +5, singleton +3, doubleton +1
• Fit, total 6–9 → 2 of opener's suit
• Fit, total 10–14 → 3 of opener's suit (limit raise)
• Fit, total 15+ → 5 of opener's suit (game)
• 4+ card suit at 1 level (6+ HCP) → bid longest (hi-5, 4-lo)
• No 1-level suit, 6–9 HCP → 1NT
• No 1-level suit, 10+ HCP, lower suit (e.g. 2♣ over 1♦) → bid it
• Balanced, 10–12 HCP → 2NT  |  13+ HCP → 3NT