Used in conjunction with 4 suit transfers
How to show slam going hands with single minor suits
1NT - 2 (alert..most likely transfer but could be start of minor suit slam try).
If opener bids 2 then a 2 bid by responder shows a slam going minor suit and opener relays to 2NT.
Responder then bids:
If responder bids 2 over openers 1NT and opener wants to super accept in hearts he bids 2 not 3 in case responder wanted to make a minor suit slam try. Any 3 level bid by responder after the 2 bid is describing the minor suit slam hands as before.. However if responder bids 2NT he is saying to opener that all I wanted to do was transfer you to hearts so opener bids 3.
The other part of Walsh comes up with a 2 bid after 1NT opener which is a transfer to clubs
3 reasons for this transfer
Another adjunct to this is way to show 5-5 minor hands and 6-4 minor hands and that is using 2NT as a transfer to diamonds.
When opener bids 3 only (not 3 showing 3 to honor) then
Obviously you cannot show 5-5 in minors when opener bids 3 instead of 3 because 3NT is used when you upgrade your hand as in 2 transfer BUT you can still show the 6-4 or 4-6 minor suit distribution