The "status" of reference data, typically associated with a flight leg. Used to indicate if any reference data is missing or not existing.
Legal values
"OK" - All relevant reference data is available.
"MissingFromData" - Reference data is missing from the data set that was used to create a flight (leg). For instance is both AircraftICAOType and AircraftIATAType are missing.
"NotInReferenceDB" - The reference data does not exist in the used reference data database. For instance an unknown AircraftRegistration.
