Quote from LongArm:
All this means is that (i) opening and closing a position on the same day is a daytrade, whereas (a.) closing an overnight position and then opening a new position in the same stock on the same day is NOT. Open-close, yes. Close-open, no.
You're equating a position to a buy, which is wrong.
While you can only have a single position in a stock it can be composed of several lots. Each lot is created with each separate purchase.
The rule clearly states that the position needs to be closed before another purchase is made in the same stock.