In Acol, if the opening bid was a major, opener can rebid his major after a Checkback inquiry to show that it has five cards rather than four and find 5-3 fits. Moreover, 1M – 2m; 2NT – 3 can also be used as Checkback Stayman. It is useful also to include an indication of range, particularly if opener's 2NT rebid is forcing to game and shows a wide points range (15-19). This is achieved by using 3 for minimum hands and 3/3/3NT for maximum hands, or vice versa. After 3, responder can still bid 3/3 to look for a 5-3 fit.
In Acol if the opening bid was a major opener can rebid his major after a Checkback inquiry to show that it has five cards rather than four and find 5-3 fits Moreover 1M – 2m; 2NT – 3 can also be used as Checkback Stayman It is useful also to include an indication of range particularly if opener's 2NT rebid is forcing to game and shows a wide points range (15-19) This is achieved by using 3 for minimum hands and 3/3/3NT for maximum hands or vice versa After 3 responder can still bid 3/3 to look for a 5-3 fit