ZipCodeGroup 

************************************** Zipcode is unique, except
possibly in requests **************************************

Element Group Information

Model

ZipCode | Zipcodes
Children: ZipCode, Zipcodes

Used By

Elements County, State, Terminal, Zipcodes
Complex Types AddressType, AgencyType, AirportType, CityType, ContinentType, CountryType, CountyType, DistanceType, DomainType, LocationFloorType, LocationSellLocationType, LocationShopType, LocationSwimmingPoolType, LocationType, RegionType, RequesterType, ShipDeckType, SlopeType, StationType, StationVehicleDropOffType, StationVehiclePickupType, StationVehicleType, StopType, TransportationMeanType

Source 

<xs:group name="ZipCodeGroup">
  <xs:annotation>
    <xs:documentation>************************************** Zipcode is unique, except possibly in requests **************************************</xs:documentation>
  </xs:annotation>
  <xs:choice>
    <xs:annotation>
      <xs:documentation>One or many</xs:documentation>
    </xs:annotation>
    <xs:element ref="ZipCode"/>
    <xs:element ref="Zipcodes"/>
  </xs:choice>
</xs:group>