CardGroup 

Cards can be of different types, such as Frequent travel cards,
commercial cards or passes

Element Group Information

Model

Card | Cards
Children: Card, Cards

Used By

Element Cards
Complex Types AgentType, AuthorType, BrandType, CarrierType, ClientType, CompanyType, CustomerType, DistributorType, GuaranteeMethodType, PersonType, SegmentActivityType, SegmentAirType, SegmentCombinedType, SegmentDocType, SegmentDocVisaType, SegmentEventType, SegmentExcursionType, SegmentFeeType, SegmentFoodType, SegmentInsuranceType, SegmentMiscellaneousType, SegmentParkingType, SegmentProductType, SegmentRailType, SegmentRoadType, SegmentServiceType, SegmentStageType, SegmentStayType, SegmentSurfaceType, SegmentTourType, SegmentTransferType, SegmentTransportationType, SegmentType, SegmentVehicleType, SegmentWaterType, StaffType, TravellerType, TripType, VehicleMakerType, VendorProviderType, VendorRetailerType, VendorType, VendorWholesaler

Source 

<xs:group name="CardGroup">
  <xs:annotation>
    <xs:documentation>Cards can be of different types, such as Frequent travel cards, commercial cards or passes</xs:documentation>
  </xs:annotation>
  <xs:choice>
    <xs:annotation>
      <xs:documentation>One or many</xs:documentation>
    </xs:annotation>
    <xs:element ref="Card"/>
    <xs:element ref="Cards"/>
  </xs:choice>
</xs:group>