[Poky]

Opponent declares 3NT. You play Lavinthal discards.

You lead a club and this kills declarer's only stopper (that becomes pretty obvoius), so your clubs become cashable.

Declarer runs high diamonds and good discarding is necessary.

In these circumstances what means:
1) high spade then low spade,
2) low heart then high heart.

Explain. TY.

[awm]

Certainly there are situations when I would not signal here, either because partner is unlikely to get in, or because I think declarer has to guess amongst several lines and is more likely to go wrong if I don't help.

However, assuming I am actively signalling, playing lavinthal:

High spade then low spade = signal for ♥, the highest side suit

High heart then low heart = signal for ♠, the highest side suit

Low heart then high heart = signal for ♣; tends to deny a ♠ card, may or may not have anything in ♥.

Low spade then high spade = signal for ♣, tends to deny a ♥ card, may or may not have anything in ♠.

[Free]

As you mentioned, you play lavinthal. No ambiguity there, you just show where your entry is using that method. High means the highest remaining suit. High ♠ asks ♥. No fancy crap, you play lavinthal...