ser-root element in SOAP response

I’m pretty new to webMethods development, SOAP and web services, so please forgive me, if the subject of this thread is too trivial. I have a question regarding calling a web service implemented in IS.
I took a WSDL (document/literal/wrapped style) and created a SOAP implementation in IS using New=>Web Service Descriptor (WS-I compliant).
Then I called the service using soapUI. Looking at the response returned, I noticed a ser-root element at the topy of the soap body:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="" xmlns:SOAP-ENC="" xmlns:xsd="" xmlns:xsi="">
      <ser-root:myMethodResponse xmlns:ser-root="">
         <tns:MyClass1 xmlns:tns="">

Does anybody know what this entity means ? I would have expected the MyClass1 element to immediately follow the Body-element.
Meanwhile I have implemented a client and server from the same WSDL using AXIS2. The response from the AXIS-Service looks the same except that the ser-root element is missing.
Furthermore the AXIS client will not accept the response from the webMethods server because of that ser-root element.
Is the generation of this element realted to my WSDL ? Or is there a way to obmit that element from the response.

Thank you in advance for your advice.

There are several bugs/issues with the WSD auto generation and soap interpretation in 7.1. Take a look at this thread for the fixes -