The «databases» folder currently contains only the user database. In the future, Air Navigation may support more than one user database. The user database file is a SQLite file and can be edited by any SQLite 3 editor. This database contains user waypoints, frequencies and runways. They are linked by the waypoint identifier. It means that if you want to input an airport with a runway and some frequencies. The relevant records must have the same value in the «waypoint_id» field. The «Documents» subfolder is where user approach charts and user PDF documents are stored. You can create subfolders inside the «Document» folder. They will appear at the top of the «Documents Browser» module in Air Navigation. The «Airport charts» folder name is reserved for documents linked to an airfield. You can copy documents inside the «Airport charts» folder but they must be grouped in a folder named with the identifier of an airfield, otherwise Air Navigation will ignore them.