The fault element contains 
exactly one value element
The value element contains 
exactly one struct element
The struct element contains 
 one faultCode and one faultString element.
The faultCode element contains 
 one int element.
The faultString element contains 
 one string element.
An Example:
HTTP/1.1 200 OK
Connection: close
Content-Length: 264
Content-Type: text/xml
Date: Tue, 29 Feb 2000 11:07:42 GMT
Server: AddressFinder 2.3
<?xml version="1.0"?>
<methodResponse>
   <fault>
      <value>
         <struct>
            <member>
               <name>faultCode</name>
               <value><int>23</int></value>
               </member>
            <member>
               <name>faultString</name>
               <value><string>Zip code does not match state</string></value>
               </member>
            </struct>
         </value>
      </fault>
</methodResponse>