Here's how it works:
XXX ==> Matches Airport XXX, IF it's a perfect match. E.g., KSFO or SFO both match perfectly to San Francisco International. "Airport" here means Airport, Heliport, or Seaport (i.e., not a navaid or fix)
XXX ==> Matches Navaid XXX, IF there is no airport/heliport/seaport...