I have actually seen people arguing about which order you are supposed to roll the ability scores in. Like, today, as well as other occasions.
Men & Magic has the abilities listed in this order: Strength, Intelligence, Wisdom, Constitution, Dexterity, Charisma. AD&D has them in a different order, and so, too, do some other versions/editions.
However, it is my contention that "3d6 in order" means "in an order" not "in this specific order". That is, you say, "I'm rolling for Strength" and then you roll for Strength, and you don't swap. It has nothing to do with rolling Strength before Intelligence, or Constitution before Dexterity. Why would it matter if you knew what your Dexterity was before you knew what your Constitution was? That's not going to affect your character. Assigning scores after you roll, on the other hand, would affect your character, which is what "3d6 in order" is meant to prevent.
Just an observation.