It was IMP. Here is South's hand: ♠Qxx, ♥xx, ♦Qxxx, ♣QJ9x Should South accept invitation (North bid 3♦) or not? I would have bid 4♠ directly. Any cards from South would be helpful, except ♣Q, even ♥Qx(x) or ♥Jxx is useful. An average 7-8 hcp hand from South would be good for game.