Roman Jump Overcalls show two-suited hands at the two-level of bidding. After 1-of-a-suit, the conventional overcalls are:

2	At least 5-5 in diamonds and hearts (the next-highest suit)
2	At least 5-5 in hearts and spades
2	At least 5-5 in spades and clubs
2NT	A strong (16+ points) two-suiter with any two suits
3	At least 5-5 in clubs and diamonds
3	Same as a 2 jump overcall, assuming a 2 jump overcall was unavailable
3	Same as a 2 jump overcall, assuming a 2 jump overcall was unavailable

The strong 2NT overcall is a relay to the cheapest unbid suit. Overcaller's rebids are:

The next-highest suit	Showing that suit and the relay suit
3NT	The two suits other than the relay suit

Examples:

1	2NT!	Pass 3!
Pass	3!			Showing diamonds and hearts.

1	2NT!	Pass	3!
Pass	3NT!			Showing hearts and spades.

Roman Jump Overcalls can also be used over preempts, although in practice they rarely come up.