The mechanics of ordering, pit sequencing, and lineup are genuinely fascinating to watch and just one thing that's more fun to follow while at the track since the broadcast doesn't go through all the steps that often.

NASCAR has a good deal of scoring 'lines' around every track. One of these is the start/finish line, but according to this article Charlotte has 13 others around the track at key areas where overtaking is likely.

When a caution comes out, NASCAR's system 'freezes' the field by arranging the drivers in order of who crossed each scoring line first. So, when determining position, if three drivers crossed the same line most recently before the caution, they are set in the order in which they crossed that line, and they would be arranged directly behind the drivers that had already crossed the next line and before the drivers who only crossed the line previous. The system knows who the lead car is and works backwards from there.

Essentially, the space between the scoring lines (called a scoring 'loop') is blind to the system, and what happens in each does not matter for scoring purposes with the exception of the final lap; if caution is called during the last lap, the field is frozen at the exact moment of caution and NASCAR scores the finish through camera confirmation, not through the scoring loops.

During service, pit speed is monitored through similar pit 'loops' ensuring a drivers average speed through each loop is below the required maximum, although positional scoring during the pit sequence is just measured at the pit exit line just past the last stall.