Re: TOS Door Colors
I've been wondering myself but I gave up after the first episodes. It seemed that red doors would indicate turbolifts exclusively (especially with a corresponding sign above) but already in "The Naked Time" there were blue (or grey) turbolift doors.
"The first duty of every Starfleet officer is to the truth, whether it's scientific truth or historical truth or personal truth! It is the guiding principle on which Starfleet is based! Jean-Luc Picard