South has a normal 1NT (balanced 12-14HCPs)

West passes

North can see a slam in ♣ s or NTs but how?

First option - try ♣ s by bidding 3♣ which is game forcing (to bail out with a weak ♣ - most people use 2♠ as a combined strength asking bid or transfer to a weak minor. The responses being 2NT as weak and 3♣ as strong, passing / correct to 3♣ /♦ if weak minor or passing or correcting to 3N if an invitation to NTs.).

Over 3♣ South will bid 3NT as he does not like ♣ s or have a 5 card major to show.

North then has to decide what does 4NT show / ask. Is it a quantitative invite to 6N or RKCB? With the long ♣ s as a source of tricks, the 6NT punt avoids any confusion.

Second Option it to bid a risky 4NT as an quantitative invitation (which would be passed) a 4♣ Gerber if you play it or with the long source of tricks to punt 6NT straight away.