<ns1:SalesOrder
xmlns:ns1="http://sap.com/CRM"
xmlns:ns2="http://customer.com/CRM/AddrExtension">
<OrderHeader>
<ShipTo>
<PartyId>1234</PartyId>
<Address ns2:Airport="SFAirport" >
<Name>Johnson</Name>
<Street>Lombard Street 10</Street>
<City>SanFrancisco</City>
<Country>US</Country>
<ns2:State>California</ns2:State>
</Address>
</ShipTo>
</OrderHeader>
<OrderItems> ... </OrderItems>
</ns1:SalesOrder>