This answer to the question Is there really no difference between up and down in ISS? says:
ISS does have a sort of 'up and down', deliberately created as part of the design. All the modules apparently have a consistent 'up' orientation in one direction. The majority of lights are in the 'ceiling' and are set up to shine 'downward'. Furthermore, all the writing on the walls is pointed in the same direction, so that it is 'right side up' in relation to the 'floor' and 'ceiling'.
But it doesn't say what directions those are.
Question: When reading "the writing on the wall" and other signage and posted messages inside the ISS, which way is up? Which direction do the lights generally come from? Direction meaning nadir, zenith, cross-track, port, stern, starboard, but please not X, Y, Z because after seeing @OrganicMarble's artwork I'll never be able to get them straight.