If Rand's quarters were on deck 12, why does her door say 3C 46? Hmmm?
Maybe it means Section 3, Deck C, Room 46. The number C in the hexadecimal numbering system is equivalent to 12 in the decimal system. I recall years ago in either my French class or Computer class the instructor stating that the French use 3 numbering systems: Octal (base 8), Decimal (base 10), and Hexadecimal (base 16). Maybe Starfleet uses hexadecimal instead of decimal.
So Section 3, Deck C, Room 46 in hexadecimal is equal to Room 3, Deck 12, Room 70 in decimal.
Just a thought,
Navigator NCC-2120 USS Entente
For all we know, they could have swiped those labels off of existing doors on the Desilu lot. You know, like cutlery from the commissary.
They are part of the "appearance of complexity" that adds to the background believability. Like stardates, GNDN labels, patches on multicolored uniforms, and windows. Details that added to the verisimilitude but without the over-the-top forethought of a TNG Tech Manual
The windows, of course, were not really intended to inform about the interior
of the ship but to inform about the scale
of the ship. As in, "Wow! Look at those windows! This thing is as tall as a twenty story building!"