. The idea, as I heard it, just applied to the sequence 1♥-(3♠), where 4♣ is used to show a good heart raise and 4♠ to show a one-suited slam try in clubs. But I also like to use it where hearts is a new suit (as described above, and also after 1NT-3♠) and also in some fairly weird spots such as 2♠-Dble-P-4♣. It is less useful if partner has opened 1♠, since you can make a cue bid below the level of game. However, I still think it's a winner after 1♠-3♥, for instance, since the good spade raises are way more common (and important) than the club hands.