Vampyr, on 2012-February-26, 04:17, said:
2NT after 2/1 either shows 15-19 or 17-19 if using 3NT to show 15-16.
Jump in NT after 1/1 shows 17-19 or 18-19.
I agree that the "jump in NT with 15+" line looked like a typo. This is what beginners are taught here, and most club players never get around to improving on it :
1x-1y-1NT = 15-16.
1x-1y-2NT = 17-18.
1x-1y-3NT = 19.
1x-1NT-2NT = 16-17.
1x-1NT-3NT = 18-19.
1x-2y-2NT = 15-17 or 15-16.
1x-2y-3NT = 18-19 or 17-19.
Reversing the last two would make a lot of sense, but I guess it's simpler to teach "minimum bid = minimum range". Also given the very light 2/1 bids some folk make, it's not all that rare to see 1x-2y-2nt-pass. Presumably the passer wouldn't want his/her partner jumping to 3NT with 15.