In 2003, “freezing the field” was implemented so drivers would no longer race back to the caution flag in all three of NASCAR’s premier series. Once the caution flag comes out, the cars’ position on the track is determined by the previous timing-and-scoring line they passed on the race track.

Pit lane remains active at the time, with the pit road speed limit in effect. Cars that are pitted from the pit road entrance to the start/finish line must reach the start/finish scoring line that is across pit road before the leader reaches the start/finish line on the track. If the cars on pit road do, in fact, reach the line first, they will not lose a lap. However, if they do not reach the line first, they will lose a lap.
 
Cars that are pitted from the start/finish line to the pit road exit must reach the pit road exit before the leader to avoid going a lap down. If a driver speeds they will not only lose a lap but also be moved to the tail end of the longest line. Also, if the leader does not slow immediately for the caution, they will receive a penalty and be sent to the tail end of the longest line.