Rules state that “the player with higher rank should play as white” : which rank is it ? The overall rank or the live rank ? They sometimes differ.
Also, if the ranks of the players are the same, then I guess that the colours are randomly attributed. How, then, can the game’s title be chosen in advance (the format is TNL - date - White vs. Black). I think it’s not really an issue but it doesn’t hurt to ask.
I think that the “rank” is the order of the list in your class listing on the nova website. Which - incidentally - is the only influence of this order that I can determine.