Bridge bidding systems continue to evolve and improve.  There have been bidding systems that opened 4 card majors.  This concept worked well when partner had 4 card support but became more problematic when partner held only 3 card support.  Bidding becomes much easier when we know that partner has at least a 5 card major but not so easy when partner opens 1 of a minor with only a 3 card suit. 

 

The negative double has had a major impact of the effectiveness of opening 5 card majors.  The negative double provides the tool to help bidders find major suit fits after a 1 of a minor opening.  Without the negative double, it would be very difficult to compete effectively.  Bergen has called negative doubles "the most important convention in modern bridge." 

 

My point is that to effectively use 5 card major bidding requires a good understanding of negative doubles.  The meanings of negative doubles and followup bids have diverse interpretations.  Many players in the zone would benefit from sharpening their negative double skills.