One Diamond Bidding System
Five Keycard A Asking System
for A asking A and trump K
4NT 5C： 0 or 3 keycards 5D ask trump Q; 5H, no; 5S, yes (for H or S or No-trump)
5D： 1 or 4 keycards 5H ask trump Q; 5S, no; 5NT, yes (for S or No-trump)
5H：2 or 5 keycards w/o Queen of trump
5S：2 or 5 keycards with Queen of trump
4NT 6C： 1A, C void
6D： 1A, D void
6H： 1A, H void, Spade trump
6H： 1A, S void, Heart trump
4NT interrupted by a bidding of LHO (D0P1）
Double： 0 or 3 keycards
Pass：1 or 4 keycards
up 1 level: 2 or 5 keycards w/o Queen of trump
up 2 level: 2 or 5 keycards with Queen of trump
for K asking K
5NT 6C： No other K except trump K
6D： 1 King except trump K
6H： 2 Kings except trump K
6S： 3 Kings except trump K
When trump suit has not been determined, the last suit before 4NT was treated as trump suit
More
1D-P-1H-P
2D-P-3D-P
4NT-P-5C-X
P-P-6D Pass ask partner to bid 6D if have Club K
1D-P-1H-P
2D-P-3D-P
4NT-P-5C-X
xx Re-double means have Club A
One Diamond Bidding System
Splinter Bid singleton or void, slam interesting
Cue bid first round control, then second round control
Splinter Bids
North South Notes
1♥ , 3 S, singleton or void, support H >= 4 cards
1♥ / 1 S, 4♣ / 4♦ C/D, singleton or void, support H/S >=4 cards
1♦ 1♥
4♣ C, singleton or void, support H >=4 cards
1♣ , 1♥
.1S, 4♦; D, singleton or void, support S >=4 cards
Cue bids
North South
1♥ 3♥
4♣ (cue) 4♦ (cue)
5♣ (cue) 5♥/6♥
♣ void, singleton ace, ace/king