The following table shows the ask and responses with each suit as trumps:
| RKB ask | 0 or 3 | 1 or 4 | 2 or 5 no Q | 2 or 5 + Q | |
|---|---|---|---|---|---|
| Hearts | 4 | 4 | 4 | 4S | 4NT |
| Spades | 4 | 4 | 4 | 4NT | 5 |
| Clubs | 4 | 4 | 4NT | 5 | 5 |
| Diamonds | 4 | 4NT | 5 | 5 | 5 |
There is a duty on an asker to go on beyond the game bid if he knows the partnership holds at least four keycards. Conversely, if the asker passes or signs off in the game bid, there are definitely two keycards missing.
| West | North | East | South | ||
|---|---|---|---|---|---|
| 2 | pass | ||||
| 3 | pass | 3NT | pass | ||
| 4 |
| 4 | none or three of CA, CK, DA, HA and SA |
| 4NT | one or four |
| 5 | two or five but not the CQ |
| 5 | two or five and the CQ |
| West | North | East | South | ||
|---|---|---|---|---|---|
| 1 | pass | 1 | pass | ||
| 2NT | pass | 4 | pass | ||
| 4 | pass | 4 | pass | ||
| ? |
bid here is that we are at least two keycards short'. If the message could be 'we are one keycard short and I've got a minimum and cold feet', opener would not know when to pass or when to bid on.