Opener - (overcall) - cue bid of overcall, is 100% strong support for opener's suit (most commonly limit raise+), because hands without support have negative doubles and new suits (if not playing negative free bids) to force not having support. (Opening bid) - overcall - (pass) - cue bid of opener's suit, is *usually* support for partner's suit, but it might not be depending on: - if you are playing some advanced scheme involving transfer responses (which sometimes shift raises to a different bid) - whether you have some method of forcing with another suit or not (for some people, cue is 100% support, you have other methods of forcing in other suits, like say jump shifting, or playing new suits at certain levels F1, or playing a transfer scheme; for other people, all their new suits are NF, and jump shifts might be fit-showing, so they have to include some non-support hands in the cue bid) Now, in response to the above cue bids, if the bid support is a minor, people will strain to show stoppers in the opp's suit anyway, because reaching 3nt is a high priority even with a minor fit, since 9 tricks is often easier than 11. Less so with major fit, though with flat hands and the opp's suit well stopped 3nt should be offered. Cue bids by *opener* though, after responder has shown some suit of their own, are assumed *not* support, and just show a strong hand often looking for a stopper for 3nt. This is because there are usually a plethora of other ways for opener to show a raise (raise to 2, 3, 4 levels, jump cue as a splinter), but no other way to show just a huge one-suiter of their own. Also cues on later rounds of auction by responder/advancer are often gropes for 3nt, when the cue isn't of the first 2 types mentioned above.