ID:

AIXM-467

target version:

AIXM 5.2

version:

1.0

last updated:

27 SEP 2021

status:

PROPOSED


Description

Additional classes, associations and data types are added in the model representing elements of the Global Navigation Satellite System (GNSS) and their augmentation systems (SBAS/GBAS). Some properties and associations are added or modified in existing AIXM classes, such as RadioFrequencyArea and GuidanceService, in order to support the coding of data related to the new satellite navigation system model.

Rationale for change

See https://aixmccb.atlassian.net/browse/AIXM-206, https://aixmccb.atlassian.net/browse/AIXM-186, https://aixmccb.atlassian.net/browse/AIXM-350

The current model is lacking the capability to represent the information about satellite navigation systems, augmentation systems and their use for air navigation. Although the list of values for the SpecialNavigationSystem.type attribute includes “GNSS”, the properties of the SpecialNavigationSystem and its associated classes are far from a complete GNSS aeronautical data model for AIS. The current model is also missing the capability to define service coverage and limitations in relation with a runway direction, which may be necessary for certain GBAS configurations.

Therefore, a dedicated set of classes and properties need to be added in the model in order to support the coding of satellite navigation systems information, as relevant for aviation use. The proposed model is based on the ICAO requirements and guidelines for the use of satellite navigation systems, as contained in the ICAO Annex 10, Vol I, 6th Edition and in the ICAO PANS-OPS document. It also takes into consideration the AIS data provision requirements for such systems. The proposed model can be summarised as follows:

  • A new SatelliteSystem class as the root of the GNSS model area, modelling both the core satellite systems (GPS, Glonass, Galileo etc.) and the satellite-based augmentation systems (such as WAAS, EGNOS, GAGAN, etc.)
  • A new GBAS class associated with the SatelliteSystem class, modelling ground augmentation systems and their operational characteristics.
  • New SatelliteService and GBASService classes associated with the SatelliteSystems and GBAS respectively, specifying the operating permission for the core and augmented system for en-route, terminal, non-precision etc. operations, including local unavailability data;
  • The new SatelliteSystem and GBAS classes need also to be included in the GuidanceService choice, as Instrument Approach Procedures, Standard Instrument Arrival (STAR) and Standard Instrument Departures (SID) procedures can use GNSS and augmentation services.

The existing RadioFrequencyArea model is used, with some improvements, in order to support the coding of the GBAS service volumes. This requires an additional “zero axis rotation” property in the CircleSector class, in order to indicate that the angles are measured from the runway centreline.

An additional correction concerns the “WAASreliable” attribute of the InstrumentApproachProcedure. Its name was initially derived from the “Wide Area Augmentation System (WAAS)”, which is an FAA-specific implementation of Satellite Based Augmentation System (SBAS). It does not seem to be still necessary, since the SatelliteService class can be used to indicate the local unavailability of an SBAS system.

Impact assessment

[FWD_MAP_1:1] Data mapping is possible and no data loss occurs when data is exchanged from a system (A) that uses AIXM 5.1.1 for output towards a system (B) that uses AIXM 5.2 for input.

[BWD_MAP_LOSS] Data mapping is possible, but some data would be lost (or converted into Notes) when data is exchanged from a system (B) that uses AIXM 5.2 for output towards a system (A) that uses AIXM 5.1.1 for input.

Change Proposal details

In the UML model, create a new package “Satellite Navigation Systems” under Navaids and Points:

  • Add a new class SatelliteSystem with <<feature>> stereotype:
    • Definition = “A satellite constellation that provides a worldwide position and time determination system and/or augmentation information for a wide coverage area.”
    • Attributes
      • type, type CodeSatelliteSystemType, definition = “Indicates the type of the service, allowing to distinguish between core GNSS systems and wide area augmentation systems.”
      • name, type TextNameType, definition = “The official name of the satellite constellation”
      • designator, type TextDesignatorType, definition = “An acronym by which the system is known to the public.”
    • Associations
      • SatelliteSystem transmitsOn RadioFrequency with
        • RadioFrequency role name “emission” (definition=”A radio communication frequency on which the satellite signal is provided.”), multiplicity 0…*;
      • SatelliteSystem isOperatedBy OrganisationAuthority with
        • OrganisationAuthority role name “operator” (definition=“The entity operating the satellite constellation.”), multiplicity 0...1
        • SatelliteSystem with multiplicity 0…*
      • SatelliteSystem augments SatelliteSystem with
        • SatelliteSystem (target) role name “augmentedSystem” (definition=”The GNSS system for which the augmented information is provided.”), multiplicity 0…*
        • SatelliteSystem (source) with multiplicity 0…*
      • SatelliteSystem hasAnnotations Note with
        • Note role “annotation” (definition = “A free text remark concerning the satellite system or one of its properties.”), multiplicity 0…*
  • Add a new class RadioFrequency with <<object>> stereotype 
    • Definition = “A specific frequency used for transmitting a radio signal.”
    • Attributes
      • frequency, type ValFrequencyType, definition = “The frequency on which the signal is transmitted.”
      • Associations
        • RadioFrequency hasAnnotations Note with
          • Note role “annotation” (definition = “A free text remark concerning the satellite service area or one of its properties.”), multiplicity 0…*
  • Add a new class SatelliteService with <<feature>> stereotype
    • Definition = “The definition of a satellite navigation service type and of the locations where it is approved for operations.”
    • Attributes
      • serviceType, type CodeSatelliteNavigationServiceType, definition = “A type of aircraft operation (such as en-route navigation, initial approach, APV-I, etc.) supported by the satellite service in a specified service area.”
    • Associations
      • SatelliteService isProvidedWith SatelliteSystem with
        • SatelliteSystem role name “satelliteSystem” (definition=”The satellite constellation for which the service is specified.”), multiplicity 0…1
        • SatelliteService multiplicity 0…*
      • SatelliteService isAvailableWithin SatelliteServiceArea with
        • SatelliteServiceArea role name “serviceArea” (definition=”The geographical area where the satellite service is available and authorised for use.”), multiplicity 0..*
      • SatelliteService isUsedFor AirportHeliport with
        • AirportHeliport role name “approachLocation” (definition = “The airport/heliport where the satellite service is used for approaches.”), multiplicity 0…*
        • SatelliteService multiplicity 0…*
        • association class SatelliteApproachOperation with
          • Definition = “The type of approach operations defined and their operational status.”
          • Attributes
            • satelliteApproachType, type CodeSatelliteApproachType, definition = “The type of final approach for which the satellite navigation system is used at the location.”
            • operationalStatus, type CodeStatusNavaidType, definition = “The availability of the service.”
          • Associations
            • SatelliteApproachOperation is a specialisation of the PropertiesWithSchedule class
            • SatelliteService hasAnnotations Note with
              • Note role “annotation” (definition = “A free text remark concerning the satellite service or one of its properties.”), multiplicity 0…*
  • Add a new class SatelliteServiceArea with <<object>> stereotype
    • Definition = “The extent of the area where the satellite service is authorised and its operational status.”
    • Attributes
      • operationalStatus, type CodeStatusNavaidType, definition = “The availability of the service.”
    • Associations
      • SatelliteServiceArea is a specialisation of the PropertiesWithSchedule class
      • SatelliteServiceArea coversTerritoryOf OrganisationAuthority
        • AuthorityOrganisation role name “country” (definition = “The State Territory for which the use of the satellite service service is authorised.”), multiplicity 0…*
        • SatelliteServiceArea multiplicity 0…*
      • SatelliteServiceArea hasExtent Surface with
        • Surface role “area” (definition = “The geographical extent of the satellite service area on the surface of the Earth.”), multiplicity 0..*
      • SatelliteServiceArea hasAnnotations Note with
        • Note role “annotation” (definition = “A free text remark concerning the satellite service area or one of its properties.”), multiplicity 0…*
  • Add a new data type class CodeSatelliteSystemBaseType with <<codelist>> stereotype
    • Definition = “A coded identifier indicating the type of the satellite system service.”
    • Values:
      • GNSS = “A core satellite constellation that provides a worldwide position and time determination system.”
      • SBAS = “Satellite-based augmentation system (SBAS). A wide coverage augmentation system in which the user receives augmentation information from a satellite-based transmitter.”
      • OTHER = Other
  • Add a new data type class CodeSatelliteSystemType (specialisation of CodeSatelliteSystemBaseType, stereotype <<DataType>>, definition: “ A complex data type that enables the provision of a NIL reason for any attribute using this type.”), attribute:
    • nilReason (type: NilReasonEnumeration)
  • Add a new data type class CodeSatelliteNavigationServiceBaseType with <<codelist>> stereotype
    • Definition = “A coded identifier designating a type of aircraft operation (such as en-route navigation, initial approach, APV-I, etc.) supported by a satellite navigation system in a specified service area”.
    • Values:
      • EN_ROUTE = “En-route navigation”
      • TERMINAL = “Terminal Area navigation, also supporting en-route navigation”
      • NPA = “Non-precision approach (NPA), also supporting Initial approach, Intermediate approach, Departure”
      • APV_I = “GNSS approach and landing operations with vertical guidance, level I”
      • APV_II = “GNSS approach and landing operations with vertical guidance, level II”
      • CAT_I = “Category I precision approach”
      • OTHER = “Other”
  • Add a new data type class CodeSatelliteNavigationServiceType (specialisation of CodeSatelliteNavigationServiceBaseType, stereotype <<DataType>>, definition: “ A complex data type that enables the provision of a NIL reason for any attribute using this type.”), attribute:
    • nilReason (type: NilReasonEnumeration)
  • In the <<CodeList>> CodeStatusNavaidBaseType, add an additional value:
    • UNRELIABLE = “Risk of both signal interruption and false information being provided”
    • RAIM_NOT_AVBL = “Receiver autonomous integrity monitoring (RAIM) not available”
  • In the CodeSpecialNavigationSystemBaseType,
    • delete the value “GNSS”

Note: the new CodeSatelliteApproachType data type is defined in AIXM-473 Change Proposal.

The resulting model for Satellite Navigation systems is shown in the following UML class diagram, with the new classes and properties highlighted in blue.



  • Add a new class GBAS with <<feature>> stereotype, Definition = “Ground-based augmentation system (GBAS). An augmentation system in which the user receives augmentation information directly from a ground-based transmitter.”.
    • Attributes
      • designator, type CodeICAOType, definition = “A coded designator, usually an ICAO location indicator, that identifies the GBAS station.”
      • name, type TextNameType, definition = “The name by which the GBAS system or its location is known.”
      • maximumUseDistance, type ValDistanceType = “(Dmax) The maximum distance (slant range) from the GBAS reference point within which pseudo-range corrections are applied by the aircraft element.”
      • flightChecked, type CodeYesNoType, definition = “An indication whether the system was flight checked.”
    • Associations
      • GBAS augments SatelliteSystem with
        • SatelliteSystem role name “augmentedSystem” (definition=”The core GNSS system or SBAS for which the augmented information is provided.”), multiplicity 0…*
        • GBAS with multiplicity 0…*
      • GBAS isOperatedBy OrganisationAuthority with
        • OrganisationAuthority role name “operator” (definition=“The entity operating the GBAS facility.), multiplicity 0...1
        • GBAS with multiplicity 0…*
      • GBAS isUsedAt AirportHeliport with
        • AirportHeliport role name “servedAirport” (definition=”An airport/heliport at which the GBAS service is provided”), multiplicity 0..*
        • GBAS with multiplicity 0…*
      • GBAS hasReferenceLocation ElevatedPoint with
        • ElevatedPoint role name “referencePoint” (definition=“The reference geographical location of the GBAS system.”), multiplicity 0…1
      • GBAS emitsFrom VDBAntenna with
        • VDBAntenna role name “antenna” (definition=“Information about the GBAS transmitting antenna.”), multiplicity 0…*
      • GBAS isOperational NavaidOperationalStatus with
        • NavaidOperationalStatus role name “availability” (definition=”The availability of the GBAS.”), multiplicity 0…*
      • GBAS hasAnnotations Note with
        • Note role “annotation” (definition = “A free text remark concerning the GBAS or one of its properties.”), multiplicity 0…*
  • Add a new class VDBAntenna with <<object>> stereotype
    • Definition = “VHF Data Broadcast antenna. A component of the GBAS system that transmits the radio signal.”
    • Attributes
      • frequency, type ValFrequencyType, definition = “The radio frequency on which the station transmits the data.”
      • emissionPower, type ValPowerType, definition = “The power of the radio signal emitted by the station antenna.”
      • polarization, type CodeSignalPolarizationType, definition = “A characteristic of the radio signal based on the geometrical orientation of the oscillations in relation with the direction of the wave.”
      • slotsTDMA, type CodeTDMAEightSlotsType, definition =”The time division multiple access (TDMA) slots allocated to the transmission signal.”
    • Associations
      • VDBAntenna hasPosition ElevatedPoint with
        • ElevatedPoint role name “location” (definition=“The geographical position of the VDB antenna”), multiplicity 0…1
      • VDBAntenna hasAnnotations Note with
        • Note role “annotation” (definition = “A free text remark concerning the VDB antenna or one of its properties.”), multiplicity 0…*
  • Add a new class GBASService with <<feature>> stereotype
    • Definition = “An operation supported by the GBAS facility within the GBAS coverage area.”
    • Attributes
      • name, type TextNameType, definition = “The name by which the GBAS Service or its location is known.”
      • approachServiceType, type CodeGBASApproachServiceType, definition = “GBAS approach service type (GAST). Designates the GBAS service types (A-D) that are supported for the approach by the ground subsystem.”
      • positioningService, type CodeYesNoType, definition = “An indication that positioning service is provided within the GBAS Service.”
      • channelRSDS, type ValChannelNumberType, definition = “The GBAS channel identifier for the positioning service (using the Reference Station Data Selector - RSDS), if provided.” (Note: proposed AIXM Business Rule - The channelRSDS should be specified only if the positioningService=’YES’)
      • regionalService, type CodeYesNoType, definition = “An indication that the service is provided as a ground-based regional augmentation system (GRAS). ”
      • approachServicePoint, type CodeCourseQualityGBASType, definition = “Indicates a service volume by means of named location along the nominal approach and/or along the runway for which GBAS performance for the supported service type(s) has been verified”
      • minimumDecisionHeight, type ValDistanceVerticalType, definition = “Indicates a service volume by means of a numerical value in feet corresponding to the minimum decision height.”
    • Associations
      • GBASService isDefinedFrom ElevatedPoint with
        • ElevatedPoint role “centrePoint” (definition=”The centre of the sectors of circle associated with the RadioFrequencyArea, when different from the location of the equipment for which the area is defined”), multiplicity 0..1
    • GBASService isProvidedWith GBAS with
      • GBAS role name “augmentationSystem” (definition=”The GBAS station that provides the service.”), multiplicity 0…1
      • GBASService with multiplicity 0..*
    • GBASService isOperationalBy NavaidOperationalStatus with
      • NavaidOperationalStatus role name “availability” (definition=”The availability of the GBAS service.”), multiplicity 0…*
    • GBASService isFor RunwayDirection with
      • RunwayDirection role “servedApproach” (definition = “The runway landing direction(s) for which the service is provided with the indicated service level.”), multiplicity 0…*
      • GBASService with multiplicity 0..*
    • GBASService hasExtent Surface with
      • Surface role “area” (definition = “The geographical extent of the GBAS service area on the surface of the Earth.”), multiplicity 0..*
    • GBASService <<no name>> EquipmentChoice with
      • GBASService role “augmentationService” (definition = “The GBAS service for which the RadioFrequencyArea information is provided.”), multiplicity 0..*
    • GBASService isInspectedOn FlightInspectionTrajectory with
      • FlightInspectionTrajetory role “flighInspectionArc” (definition = “An arc of circle at a predefined distance and altitude from the GBAS reference point used for flight inspection”), multiplicity 0…*
    • GBASService hasAnnotations Note with
      • Note role “annotation” (definition = “A free text remark concerning the GBAS service or one of its properties.”), multiplicity 0…*
  • In the RadioFrequencyArea class:
    • modify the class definition = “A limitation, such as coverage, usability, etc., of a navaid equipment or Global Navigation Satellite System (GNSS), service frequency or service volume.”
    • modify the definition of the type attribute
      • definition = “A code indicating the type of radio navigation aid or Global Navigation Satellite System (GNSS) limitation.”
  • In the CircleSector <<object>> add the following property
    • Attribute
      • zeroAxisRotation, type, ValBearingType, definition = “Rotation of the zero axis from the magnetic of true North, allowing to specify a zero axis that is parallel to a runway centreline.“
  • Add a new class FlightInspectionTrajectory with <<object>> stereotype
    • Definition = “A trajectory flown in order to verify the operational coverage of the radio signal of a navaid, GNSS or augmentation system”
    • Attributes
      • name, type TextNameType, definition = “The name by which the FlightInspectionTrajectory is identified.”
      • elevation, type ValDistanceVerticalType, definition = “The altitude or height at which the trajectory is flown”
      • elevationReference, type CodeVerticalReferenceType, definition = “The reference surface for the trajectory elevation. For example, Mean Sea Level, Ground, standard pressure, etc.”
      • arcRadius, type ValDistanceType, definition = “The radius of the arc curve, when applicable, measured from the associated service centre point”
    • Associations
      • FlightInspectionTrajectory hasTrajectory Curve with
        • Curve role “groundTrajectory” (definition = “The projection of the flight inspection trajectory on the surface of the Earth.”), multiplicity 0..*
      • FlightInspectionTrajectory hasAnnotations Note with
    • Note role “annotation” (definition = “A free text remark concerning the FlightInspectionTrajectory or one of its properties.”), multiplicity 0…*
  • Add a new data type class CodeGBASApproachServiceBaseType with <<DataType>> stereotype
      • Definition = “A coded identifier designating an approach service type supported by a GBAS service”.
      • Pattern: “[A-D]*”, minLength:1, maxLength:4.
  • Add a new data type class CodeGBASApproachServiceType (specialisation of CodeGBASApproachServiceBaseType, stereotype <<DataType>>, definition: “ A complex data type that enables the provision of a NIL reason for any attribute using this type.”), attribute:
    • nilReason (type: NilReasonEnumeration)
  • Add a new data type class CodeSignalPolarizationBaseType with <<codelist>> stereotype
    • Definition = “A coded identifier indicating a characteristic of a radio signal based on the geometrical orientation of the oscillations in relation with the direction of the wave.”
    • Values:
      • H = Horizontally polarized signal.
      • E = Elliptically polarized signal.
      • OTHER = Other
  • Add a new data type class CodeSignalPolarizationType (specialisation of CodeSignalPolarizationBaseType, stereotype <<DataType>>, definition: “ A complex data type that enables the provision of a NIL reason for any attribute using this type.”), attribute:
    • nilReason (type: NilReasonEnumeration)
  • Add a new data type class CodeTDMAEightSlotsBaseType with <<DataType>> stereotype
    • Definition = “A coded identifier indicating the time division multiple access (TDMA) slots allocated to a transmission signal in the case of a 8-slots configuration.”
    • pattern = “[A-H]{1,8}”
  • Add a new data type class CodeTDMAEightSlotsType (specialisation of CodeTDMAEightSlotsBaseType, stereotype <<DataType>>, definition: “ A complex data type that enables the provision of a NIL reason for any attribute using this type.”), attribute:
    • nilReason (type: NilReasonEnumeration)
  • Add a new data type class ValPowerBaseType with <<DataType>> stereotype (derived from XMLSchemaTypes::decimal)
    • Definition =”The amount of energy transferred or converted per unit time.”
  • Add a new data type class ValPowerType (specialisation of ValPowerBaseType, stereotype <<DataType>>,  definition: “ A complex data type that enables the provision of unit of measurement a NIL reason for any attribute using this type.”), attribute:
    • uom (type: UomPowerType)
    • nilReason (type: NilReasonEnumeration)
  • Add a new data type class UomPowerType with <<Codelist>> stereotype
    • Definition =”A unit of measurement for power values.”
    • Values:
      • WATT = “Watt”
      • DBM = “Decibel milliwatt”
      • OTHER = “Other”
  • Add a new data type class CodeCourseQualityGBASBaseType with <<codelist>> stereotype
    • Definition = “A coded identifier indicating a GBAS service volume by means of a named location along the nominal approach and/or along the runway. Source: ICAO Annex 10, Vol I, Attachment D, 7.1.4.2.1”
    • Values:
      • A = “GBAS Point ‘A’. A point on a GBAS final approach segment measured along the extended runway centre line in the approach direction a distance of 7.5 km (4 NM) from the threshold.”
      • B = “GBAS Point ‘B’. A point on the GBAS final approach segment measured along the extended runway centre line in the approach direction a distance of 1 050 m (3 500 ft) from the threshold.”
      • C = “GBAS Point ‘C’. A point through which the downward extended straight portion of the nominal GBAS final approach segment passes at a height of 30 m (100 ft) above the horizontal plane containing the threshold.”
      • D = “GBAS Point ‘D’. A point 3.7 m (12 ft) above the runway centre line and 900 m (3 000 ft) from the threshold in the direction of the GNSS azimuth reference point (GARP).”
      • E = “GBAS Point ‘E’. A point 3.7 m (12 ft) above the runway centre line and 600 m (2 000 ft) from the stop end of the runway in the direction of the threshold.”
      • S = “GBAS Point ‘S’. A point 3.7 m (12 ft) above the runway centre line at the stop end of the runway.”
      • T = “GBAS reference datum (Point ‘T’). A point at a height specified by TCH located above the intersection of the runway centre line and the threshold.”
      • OTHER = Other
  • Add a new data type class CodeCourseQualityGBASType (specialisation of CodeCourseQualityGBASBaseType, stereotype <<DataType>>, definition: “ A complex data type that enables the provision of a NIL reason for any attribute using this type.”), attribute:
    • nilReason (type: NilReasonEnumeration)

The resulting GBAS model  is shown in the following UML class diagram, with the new classes and associations highlighted in blue:


  • Add the following associations to the <<choice>> GuidanceService class
    • GuidanceService uses SatelliteSystem with
      • SatelliteSystem role name “satelliteService” (“The guidance service is provided by a satellite system (GNSS core or SBAS)”), multiplicity 0...1
      • GuidanceService multiplicity 0…*
    • GuidanceService uses GBAS with
      • GBAS role name “groundAugmentedGNSS” (“The guidance service is provided by a Ground Based Augmentation Station”), multiplicity 0...1
      • GuidanceService multiplicity 0…*
  • In the InstrumentApproachProcedure class
    • Delete the WAASReliable attribute

The resulting GuidanceFacility model is shown in the following UML class diagram, with the new classes and associations highlighted (Note: the multiplicity of the GuidanceService class in the association to Procedure is 0..1 on this diagram. This takes into consideration the Change Proposal AIXM-419):

Mapping AIXM 5.1.1 to AIXM 5.2 (forward)

[MAPC-99] No mapping is possible or justified. This is a completely new model for GNSS elements.

Mapping AIXM 5.2 to AIXM 5.1.1 (backward)

[MAPC-02] Applied only for Procedure specialisations that have the new associations for GuidanceService. From the three backward mapping options discussed for this case, the first two (discard the value or use an extension) are straightforward and do not need any further details. The 3rd option (backward mapping into a Note) is detailed in order to provide a complete description of this case and its conversion option:

  • For each InstrumentApproachProcedure, StandardInstrumentDeparture or StandardInstrumentArrival that has guidanceFacility_satelliteService:
    • Remove the guidanceFacility_satelliteService element;
    • Add an annotation.Note associated with the owner class having
  • purpose=“OTHER:BACKWARD_MAPPING”;
  • LinguisticNote.note=”guidanceFacility uses SatelliteService: <value of related SatelliteSystem.type>, <value of related SatelliteSystem.name>, <value of related SatelliteSystem.designator>”
  • propertyName=”guidanceFacility_specialNavigationSystem”


  • For each InstrumentApproachProcedure, StandardInstrumentDeparture or StandardInstrumentArrival that has guidanceFacility_groundAugmentedGNSS:
    • Remove the guidanceFacility_groundAugmentedGNSS element;
    • Add an annotation.Note associated with the owner class having
  • purpose=“OTHER:BACKWARD_MAPPING”;
  • LinguisticNote.note=”guidanceFacility uses GBAS : <value of related GBAS.designator>”
  • propertyName=”guidanceFacility_specialNavigationSystem”


[MAPC-99] No mapping possible for the rest of the data. The only other option in the previous version is the use of an extension, for those systems that are interested to use the new capability without a complete transition to the new version. Therefore, the following elements shall be removed from the file in order to ensure a valid AIXM 5.1.1 output:

  • SatelliteSystem
  • SatelliteService
  • GBAS
  • GBASService
  • RadioFrequencyArea that is associated (limits) GBASService

Mapping example

(Note: for mapping test data see: https://github.com/aixm/mapping_52_511/tree/master/AIXM-xxx) 

AIXM 5.2AIXM 5.1(.1)
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