If partner has not yet called, then Chilli pre-empts are sound: obstructive but disciplined, so that partner can safely make a forward move with a strong hand. The pre-emptor will usually have six trumps for a two-level pre-empt, seven at the three-level and so on. The hand will have some values - from six or so up to just below a minimum opening hand - and it won't have a concealed major suit.
| West | North | East | South | ||
|---|---|---|---|---|---|
 985 | pass | ||||
 KQ9864 | ? | ||||
 106 | |||||
 K5 |
at any vulnerability, a sound pre-emptive opening. Partner could still have a good hand.If partner has already passed and leftie has another bid, we switch to unsound pre-empts: totally unilateral and destructive, with probably one less trump than a sound pre-empt, and a much wider range – from complete rubbish to a sound opening bid, and maybe with a concealed major. Partner is not invited to engage in constructive dialogue – only to pass or raise pre-emptively with enough trumps.
| West | North | East | South | ||
|---|---|---|---|---|---|
| 985 | pass | pass | |||
| KQ9864 | ? | ||||
| 106 | |||||
| K5 |
if vulnerability permits. Partner has passed and we can and should act unilaterally. We might make the same bid without the heart honours or with an extra ace.In the pass-out seat, you can prevent the opponents reaching a better contract simply by passing, so now pre-empts are positive: primarily constructive with a sound number of trumps and expecting to go positive more often than not.