VPF Narrative Table for "Airport Facilities Points":
Information on airports/airfields (GB005) was derived from the DAFIF (Digital Aeronautical Flight Information File) and TINT (Target Intelligence) in areas where such data was available. Each airfield's DAFIF reference number was placed in the 'na3' (classification name) attribute field. Only airfields which had at least one hard surface runway longer that 3,000 feet (910 meters) were collected.