Well, this 4NT bid by an intelligent partner simply cannot be Blackwood. Although we do play some kind of Ace asking enquiry it can logically only be used when there is an agreed trump suit (else how can partner sign-off below slam level if I don't have the requisite number of Aces?). Anyway, the bulk asking for Aces and Kings is an inept method of slam bidding, and should be used sparingly. The method reduces one member of the partnership to an automaton and causes the Blackwooder to make the final decision on inadequate information. So, therefore, on this hand 4NT must be an invitational bid in No-trumps. Partner probably has a flattish 19 points in which is a four card major or two. Now, is my hand suitable for a slam?