Roman 2

Opening a Roman 2 shows any 4-4-4-1 or any 5-4-4-0 distribution with 17+ HCPs.

Responder can bid a suit with a weak hand, or bid 2N to ask opener to bid his short suit, which tells responder that opener has at least 4 cards in each of the other suits.

See Mini-Roman (the same convention with 11-15 HCP) for responses and rebids.