This is a specialization of the string class and it inherits all attributes and associations of that class.

Name	Data Type	Definition
inapplicable	string	there is no value
missing	string	the correct value is not readily available to the sender of this data. Furthermore, a correct value may not exist
template	string	the value will be available later. The value is announced in advance. For example, the value is provided in a NOTAM.
unknown	string	the correct value is not known to, and not computable by, the sender of this data. However, a correct value probably exists
withheld	string	the value is not divulged
other	string	Other reason for null value.

CodeATCReportingType , CodeAerialRefuellingPointType , CodeAerialRefuellingPrefixType , CodeAerialRefuellingType , CodeAircraftCategoryType , CodeAircraftEngineNumberType , CodeAircraftEngineType , CodeAircraftGroundServiceType , CodeAircraftICAOType , CodeAircraftStandType , CodeAircraftType , CodeAircraftWingspanClassType , CodeAirportHeliportCollocationType , CodeAirportHeliportDesignatorType , CodeAirportHeliportType , CodeAirportWarningType , CodeAirspaceActivityType , CodeAirspaceAggregationType , CodeAirspaceClassificationType , CodeAirspaceDependencyType , CodeAirspaceDesignatorType , CodeAirspacePointPositionType , CodeAirspacePointRoleType , CodeAirspaceType , CodeAltitudeAdjustmentType , CodeAltitudeUseType , CodeApproachEquipmentAdditionalType , CodeApproachGuidanceType , CodeApproachLightingICAOType , CodeApproachLightingType , CodeApproachPrefixType , CodeApproachType , CodeApprovalType , CodeApronElementType , CodeApronSectionType , CodeArcDirectionType , CodeArrestingGearEnergyAbsorbType , CodeArrestingGearEngageDeviceType , CodeAuralMorseType , CodeAuthorityRoleType , CodeAuthorityType , CodeAviationStandardsType , CodeBearingType , CodeBuoyType , CodeCardinalDirectionType , CodeCheckpointCategoryType , CodeColourType , CodeCommunicationChannelType , CodeCommunicationDirectionType , CodeCommunicationModeType , CodeComparisonType , CodeContaminationType , CodeCourseQualityILSType , CodeCourseType , CodeDMEChannelType , CodeDMEType , CodeDayType , CodeDeclaredDistanceType , CodeDesignStandardType , CodeDesignatedPointDesignatorType , CodeDesignatedPointType , CodeDirectionReferenceType , CodeDirectionTurnType , CodeDirectionType , CodeDistanceIndicationType , CodeEmissionBandType , CodeEquipmentAntiCollisionType , CodeEquipmentUnavailableType , CodeFacilityRankingType , CodeFinalGuidanceType , CodeFireFightingType , CodeFlightDestinationType , CodeFlightOriginType , CodeFlightPurposeType , CodeFlightRestrictionDesignatorType , CodeFlightRestrictionType , CodeFlightRuleType , CodeFlightStatusType , CodeFlightType , CodeFlowConditionOperationType , CodeFreeFlightType , CodeFrictionDeviceType , CodeFrictionEstimateType , CodeFuelType , CodeGeoBorderType , CodeGradeSeparationType , CodeGroundLightingType , CodeGuidanceLineType , CodeHeightReferenceType , CodeHelicopterPerformanceType , CodeHoldingCategoryType , CodeHoldingUsageType , CodeHoldingUseType , CodeIATAType , CodeICAOType , CodeILSBackCourseType , CodeIntegrityLevelILSType , CodeIntensityStandByType , CodeLanguageType , CodeLevelSeriesType , CodeLevelTableDesignatorType , CodeLevelType , CodeLightHoldingPositionType , CodeLightIntensityType , CodeLightSourceType , CodeLightingJARType , CodeLoadingBridgeType , CodeLocationQualifierType , CodeLogicalOperatorType , CodeMLSAzimuthType , CodeMLSChannelType , CodeMarkerBeaconSignalType , CodeMarkingConditionType , CodeMarkingStyleType , CodeMeteoConditionsType , CodeMilitaryOperationsType , CodeMilitaryRoutePointType , CodeMilitaryStatusType , CodeMilitaryTrainingType , CodeMinimaFinalApproachPathType , CodeMinimumAltitudeType , CodeMinimumHeightType , CodeMissedApproachType , CodeNDBUsageType , CodeNavaidDesignatorType , CodeNavaidPurposeType , CodeNavaidServiceType , CodeNavigationAreaRestrictionType , CodeNavigationAreaType , CodeNavigationEquipmentType , CodeNavigationSpecificationType , CodeNitrogenType , CodeNorthReferenceType , CodeNotePurposeType , CodeObstacleAreaType , CodeObstacleAssessmentSurfaceType , CodeObstructionIdSurfaceZoneType , CodeOilType , CodeOperationAirportHeliportType , CodeOperationManoeuvringAreaType , CodeOrganisationDesignatorType , CodeOrganisationHierarchyType , CodeOrganisationType , CodeOxygenType , CodePARType , CodePCNMethodType , CodePCNPavementType , CodePCNSubgradeType , CodePCNTyrePressureType , CodePassengerServiceType , CodePilotControlledLightingType , CodePositionInILSType , CodePrimaryRadarType , CodeProcedureAvailabilityType , CodeProcedureCodingStandardType , CodeProcedureDistanceType , CodeProcedureFixRoleType , CodeProcedurePhaseType , CodeProtectAreaSectionType , CodeRNPType , CodeRVRReadingType , CodeRVSMPointRoleType , CodeRVSMType , CodeRadarServiceType , CodeRadioEmissionType , CodeRadioFrequencyAreaType , CodeRadioSignalType , CodeReferenceRoleType , CodeReflectorType , CodeRelativePositionType , CodeRoadType , CodeRouteAvailabilityType , CodeRouteDesignatorLetterType , CodeRouteDesignatorPrefixType , CodeRouteDesignatorSuffixType , CodeRouteNavigationType , CodeRouteOriginType , CodeRouteSegmentPathType , CodeRouteType , CodeRuleProcedureTitleType , CodeRuleProcedureType , CodeRunwayElementType , CodeRunwayMarkingType , CodeRunwayPointRoleType , CodeRunwayProtectionAreaType , CodeRunwaySectionType , CodeRunwayType , CodeSafeAltitudeType , CodeSegmentPathType , CodeSegmentTerminationType , CodeServiceATCType , CodeServiceATFMType , CodeServiceGroundControlType , CodeServiceInformationType , CodeServiceSARType , CodeSideType , CodeSignalPerformanceILSType , CodeSpecialDateType , CodeSpecialNavigationChainDesignatorType , CodeSpecialNavigationStationType , CodeSpecialNavigationSystemType , CodeSpeedReferenceType , CodeStandbyPowerType , CodeStatusAirportType , CodeStatusAirspaceType , CodeStatusConstructionType , CodeStatusNavaidType , CodeStatusOperationsType , CodeStatusServiceType , CodeSurfaceCompositionType , CodeSurfaceConditionType , CodeSurfacePreparationType , CodeSystemActivationType , CodeTAAType , CodeTACANChannelType , CodeTLOFSectionType , CodeTaxiwayElementType , CodeTaxiwaySectionType , CodeTaxiwayType , CodeTelecomNetworkType , CodeTimeEventCombinationType , CodeTimeEventType , CodeTimeReferenceType , CodeTrajectoryType , CodeTransponderType , CodeUUIDType , CodeUnitDependencyType , CodeUnitType , CodeUpperAlphaType , CodeUsageLimitationType , CodeVASISType , CodeVORType , CodeValueInterpretationType , CodeVerticalDatumType , CodeVerticalReferenceType , CodeVerticalStructureMarkingType , CodeVerticalStructureMaterialType , CodeVerticalStructureType , CodeVisualDockingGuidanceType , CodeWakeTurbulenceType , CodeWorkAreaType , CodeYesNoType , DateMonthDayType , DateTimeType , DateType , DateYearType , NoNumberType , NoSequenceType , TextAddressType , TextDesignatorType , TextInstructionType , TextNameType , TextNoteType , TextPhoneType , TextPropertyNameType , TextRemarkType , TextSIDSTARDesignatorType , TimeType , ValAlarmLimitType , ValAngleType , ValBearingType , ValChannelNumberType , ValDepthType , ValDistanceSignedType , ValDistanceType , ValDistanceVerticalType , ValDurationType , ValFLType , ValFrequencyType , ValFrictionType , ValHexType , ValLCNType , ValLightIntensityType , ValMagneticVariationChangeType , ValMagneticVariationType , ValPCNType , ValPercentType , ValPressureType , ValSlopeType , ValSpeedType , ValTemperatureType , ValWeightType , XHTMLType