Regarding that "3F 127" sign there, later recycled for McCoy's cabin... Did we ever have dialogue that would have directly contradicted the idea that either the first or the second digit in such signage indicates the deck? That is, that McCoy lived on Deck 3=C (like Spock in ST2) or Deck F=6?
And, according to dialog and the signs in the corridors seen in "Day of the Dove", Officer's Quarters are located on deck six.
Hmm. What dialog, exactly?