Zone 1 and Zone 2 are located within the property of the Green Bank Observatory. The entire property is designed as Zone 1 except small portions (such as housing, visitor, and laboratory areas) that are designed as Zone 2. Zone 1, also called Radio Astronomy Instrument Zone, restricts intentional radiators to only those are deemed essential. All unintentional radiators must be operated within the recommendations on protection criteria used for radio astronomical measurements. Gasoline-powered motor vehicles are prohibited in Zone 1 as their spark-ignition engines generate significant radio interference, resulting in the requirement that all vehicles and equipment be diesel-powered. Zone 2, also called Observatory Building Zone, allows intentional radiators licensed by National Radio Quiet Zone, but not other radiators such as Wi-Fi, cordless phones, and other wireless equipment. Certain types of unintentional radiators are allowed, however digital cameras are prohibited, although film photography is allowed.