The Romex system is a contract bridge bidding system designed by Mexican bridge expert George Rosenkranz.[1] Key features of Romex are the multiple meanings attributed to certain bids, such as the dynamic one notrump and the Mexican two diamonds.
The dynamic one notrump opening indicates either:
The most common responses to the dynamic one notrump opening are:
Higher-level responses indicate control count.
A consequence of the use of the dynamic notrump is that the 1NT rebid by opener becomes wide-range (typically 12-16 hcp). With game invitational values or better, responder reacts to such a rebid with a 2♣ checkback convention to ask opener to further describe his hand.
This opening indicates one of four hands:
One-level and 2♣ openings are as per Standard American with 3+ minors and 5+ majors and limited by the failure to open one notrump.
Romex employs special asking bids in lieu of cuebidding, and for slam investigation.
