A null structure, like the following::

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"> <s:Header> </s:Header> <s:Body> <RetStructS1 xmlns="http://tempuri.org/"> <inStructS1 xmlns:d4p1="http://schemas.datacontract.org/2004/07/XwsInterop.SoapWsdl.ComplexDataTypes.XmlFormatter.Service.Indigo" i:nil="true" xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="" /> </RetStructS1> </s:Body> </s:Envelope>

results in a member being set to null instead of the structure itself:

<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"> <env:Body> <ns1:RetStructS1Response xmlns:ns1="http://tempuri.org/"> <RetStructS1Result xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <ns_name:name xmlns:ns_name="http://schemas.datacontract.org/2004/07/XwsInterop.SoapWsdl.ComplexDataTypes.XmlFormatter.Service.Indigo" xsi:nil="1"> </ns_name:name> </RetStructS1Result> </ns1:RetStructS1Response> </env:Body> </env:Envelope>