Template documentation

For now, this template just includes the four-character airport code verbatim. The template is in the format {{FAA_LID|airportcode}}, enclosed in double-braces, bar-separated. For example, {{FAA_LID|3W2}} for FAA LID: 3W2, Put-in-Bay Airport. FAA LIDs are used for U.S. airports, and often times are the only designation available for small airports.