Note-this class includes image forming devices and associated aids, their subassemblies and components, utilizing passive and/or active techniques for detection, observation, and identification of terrain and objects at night, while maintaining concealment afforded by darkness. includes items having multiapplication for purposes of fire control, and/or night observation, and/or detection. excluded from this class are items for which more specific classifications are suitable as prescribed by the structure and indexes of the fsc. Includes sighting and observation devices, target detectors and locators, remote viewing systems utilizing heat radiation emitted from object(s), associated radiation sources, image converters and image intensifiers, optical cells and other components designed for night vision equipment. holders and lens used with infrared equipment are also included in this fsc. Excludes optical sighting devices which incorporate both day and night viewing characteristics within an integral unit for fire control purpose, nonnight vision type items designed for use with guided missiles, communications, or laboratory equipment, and optical elements, such as lens, prisms, windows.