Regarding the NL, yes you can have a pos score on a down stock. Take stock XYZ, it gaps down 10% on the open and goes straight up, confirms an A up and closes at the high. Stock is still down 5% on the day with a +2 score.
Yes, I was thinking about the gap scenario but disregarded its influence to the NL as most markets are open 24/5 these days. Weekend gaps - yes. But do they really significantly affect the NL since their frequency is only 1/5 and the gaps are not always that large. That's why I was wondering if the location settlement is that important. E.g. 3 good A ups could be counted as +6 on the number line, but if market settled in the lower part of the OR on all 3 occasions, you'd see a lowering price.