Color-Coded For Your Convenience: Played straight in all the usual locations: indicator lights, transit routes, components and tool-heads, plugs and sockets, signs, departments on uniforms, logos, etc., etc.  Made more complicated, though, by the local spectrum including two ultraviolets (no, that plain white cloak is not plain white) and an infrared as visible colors; visitors with greater than merely human or lesser spectral bandwidth are still, however, lucky that the number of species that can eyeball the difference between true green and blue-and-yellow-mixed is small, otherwise this would get Very Difficult Indeed.