1ª - 3NT or 1©- 3ª distributional raise with at least 4 trump and at least 3 total controls.

Opener bids a new suit where he does not need shortness (after 1©-3ª then 3NT is replacement for ª).

If responder is short in that suit he signs off. If not he has a 4 step response around the sign off suit.

1^st step = singleton lower

2^nd step = singleton higher

3^rd step = void lower

4^th step= void higher

POLOWAN

1ª - 3NT or 1©- 3ª = mini splinter relay asks