2NT-3C (FOUR-CARD MAJORS)
|Pass after overcall||might be passing for penalties, hoping for a reopening takeout double from partner|
|Pass after double||Shows a non-horrible four-card suit, willing to play in the doubled conventional bid if partner has trumps too.|
|Redouble||To play, good five-card suit, but partner's allowed to take it out if unsuitable.|
|Diamonds||denies a four-card major|
|Spades||four spades, denying four hearts|
FINN AND DAVID'S DEFENCE TO 2NT 3C
All such bids are to be assumed to be weak and pre-emptive, so a reply from partner is non-forcing.