Just found out that Kantar plays the same treatment as we do with minors over 2NT but he adds a transfer element . Is it worth taxing our memory to implement it ? Also see the 4NT bid by responder after the 3 relay to 3NT and of course Kantars KCB element in these sequences .
RESPONDING TO 2NT WITH SLAM INVITATIONAL MINOR SUIT HANDS It has always been a problem to show the minors in response to a 2NT opening bid.
2NT 3 (forces 3NT and starts minor suit slam oriented auctions)
The reason for having 4 mean diamonds and 4 mean clubs is to allow the strong hand to be the declarer in case the opener is interested in playing in that suit.
An example of a 3 bid followed by 4 might be: xx Jx AQ9xxx K10x
An example of a 3 bid followed by 4 might be: xx x AJxxx KQJxx
An example of a 3 bid followed by 4NT might be: Kxx xx Axxx AJxx
After responder makes a slam try, it is now up to the opener to decide whether to sign off, usually with 4NT or try for slam.
After responder bids 4, a slam try in diamonds, if opener is interested in asking for keycards, he bids 4
After responder shows a singleton HEART, 4 by the opener can be used as "double keycard" asking for aces, kings, and queens of both minors!
As most players don't use that, and probably have never even heard of it, it is easier to play 4NT as a signoff after a singleton showing response and leaping to slam with a maximum plus a fit for one of the minors. If opener retreats to five of a minor it is up to responder to bid the slam with a maximum.
"in either major, 4NT by the opener is to play. If opener is interested in slam in either minor, he has to bid it.