PetGroup 

To describe behaviour with Pet, wether Pets are allowed, with a
surcharge, for different types of pets ...

Element Group Information

Model

Pet | Pets
Children: Pet, Pets

Used By

Element Pets
Complex Types AccomodationType, AgentType, AuthorType, BrandType, CabinType, CarrierType, ClientType, CompanyType, CustomerType, DistributorType, GuaranteeMethodType, HotelType, PersonType, RestaurantType, RoomBedroomType, RoomKitchenType, RoomMeetingRoomType, RoomStorageType, RoomType, ShipType, StaffType, TravellerType, VehicleMakerType, VendorProviderType, VendorRetailerType, VendorType, VendorWholesaler

Source 

<xs:group name="PetGroup">
  <xs:annotation>
    <xs:documentation>To describe behaviour with Pet, wether Pets are allowed, with a surcharge, for different types of pets ...</xs:documentation>
  </xs:annotation>
  <xs:choice>
    <xs:annotation>
      <xs:documentation>One or Many</xs:documentation>
    </xs:annotation>
    <xs:element ref="Pet"/>
    <xs:element ref="Pets"/>
  </xs:choice>
</xs:group>