Run supportInfo "i:airportSide", the output is (formatting added):
[[ "u", "airportside", "airportSide", "Checks a side of the airport.", "airportSide 0", "west", "NOTHING", "", "SCALAR,OBJECT", "airportSide airportId" ]]
While the command actually returns a side: typeName (airportSide 0) // "SIDE"