 If there are two four-card suits (one being clubs), the opener bids the higher first and then 3NT for the clubs if no fit is found.The opener's 2NT is a limited bid and the responder has not shown the strength of his hand, therefore the responder will control how high the bidding goes, game or prospecting for a slam, and the suit to be played.The main advantage of this convention is that it becomes easier to reach minor-suit slams.