UPDATE: I thought these were just simple parking tags, but anonymous gives us the real story:
Dort Hwy. parking lot tags - A time honored tradition to recognize loyalty, length of service and salary level (and to keep the troops in line). When hiring in, everyone started out in the east lot, off Averill Ave. It was a long, twice daily, walk thru the factory to get to and from your work area on Dort Hwy. The Dort Hwy south lot was a first stop on your way to parking lot gold. It could be attained if you kept your nose clean and advanced in rank just enough to qualify as being one of the established herd. After years of struggle and hardship, the lucky ones finally had enough salary and length of service points to qualify for a north lot pass, right next to the main gate on Dort Hwy. Of course someone had to retire or die, before you could realize your parking dream. The north Dort Hwy parking lot was only superseded by garage parking, under the main office building, which was reserved for the uncoded executives. If and when you earned a north lot pass, you walked with your head just a little higher (and tended to go out for lunch; just to watch that gate go up and down).