This “HowTo” is a short guideline, what addon-designer should be consider, when they want to use the underlying navdata (default ones or from some other provider).
You should try to split your scenery from the navdata. The reason for that is, that whenever something changed in the navdata, you must also update your scenery on-time not be outdated (and also your user must update his scenery file). To include terminal-waypoints, terminal-procedures, … is a more or less bad design and should be avoided. ASOBO/MS and we too, update the navdata all 28 days as in real-world.
It is highly recommanded, to use the “DeleteAirport” element, even when the airport doesn´t exist in the default data. You can´t be sure, that someone else build the same airport and when you don´t include it, you see the “double scenery” effect (double runways, markings, lights, …).
To avoid this, add following in your airport project:
<DeleteAirport deleteAllApronLights="TRUE" deleteAllAprons="TRUE" deleteAllHelipads="TRUE" deleteAllRunways="TRUE" deleteAllStarts="TRUE" deleteAllTaxiways="TRUE" deleteAllBlastFences="TRUE" deleteAllJetways="TRUE" deleteAllControlTowers="TRUE" deleteAllPaintedElements="TRUE" deleteAllLightSupports="TRUE" deleteAllTaxiwaySigns="TRUE" />
With this statement, you can be sure, that your scenery (if it´s high enough in the scenery-hierarchy) overrule all other sceneries which are lower but your scenery uses the navdata which are installed (3rd party or the default data).