Back in the mid- 1980's, when we embarked on building the second batch of passenger cars, the subject of color came up pretty quickly. We settled on "Pullman Green".
OK, what EXACTLY is Pullman Green?
We went to the Dupont Paint dealer in ABQ. He got on his computer and amazingly enough he had color formulas for not one version of Pullman Green, but four of them. He graciously mixed up a pint can each for us to try out. I recall one being very brown (like UPS Brown), one being very green, one more brown than green, and more green than brown (which is what we picked).
The point being that at one time all four were correct.