Standards for Night Vision Imaging Systems
NVIS stands for Night Vision Imaging Systems, a technology needed for safe flight during nighttime. NVIS devices intensify and magnify light at night and often come as helmet-mounted goggles. The outside then may look green, and instruments and displays, of course, must be of a certain type to be optimally visible with NVIS. NVIS colors for aviation are defined in MIL-L-85762A. The standard defines the exact chromatic limits for green, yellow and red. See exerpt from the Digital Avionics Handbook.