Australian Asking Bid

Used to investigate the quality of partner's trump holding after a suit has been agreed. After agreeing upon a suit, partner may bid the cheapest level of notrump available to make the inquiry. Responder then bids in steps as follows
Cheapest level of trump = neither the queen nor king of trumps
1st step = queen
2nd step = king
3rd step = king and extra length
4th step = king and queen
5th step = king and queen and extra length

IMPORTANT NOTE: The trump suit is not counted as a step (you must skip over it when counting).

E.G.,

1S pass 2C pass
2H pass 3S pass
3NT! pass 4NT! pass
6S p/o

The 3NT bid was the cheapest notrump available, so it was the asking bid.

The 4NT bid was the FOURTH step (remember, don't count the spade as a step), showing the king and queen of trumps.