A disturbed 4NT is Roman Keycard Blackwood (RKB), agreeing the last shown suit and making the auction fit. RKB is discussed in fit auctions.
A disturbed 5NT requests partner to 'pick a slam'.
| West | North | East | South | ||
|---|---|---|---|---|---|
1 | 4 | ||||
| 4NT |
| West | North | East | South | ||
|---|---|---|---|---|---|
3 | dbl | 5 | |||
| 5NT |
.