title: MustUnderstand attribute in WCF response causes error for Java/Axis client
body: <p>We have developed a WCF4 service with usernameToken authentication that is being consumed by a Java/Axis client (that we have no control over).</p>
  
  <p>I can see that the body of the request coming in looks like this...</p>
  
  <pre><code>&lt;soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"&gt;
    &lt;soapenv:Header&gt;
      &lt;wss:Security xmlns:wss="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"&gt;
        &lt;wss:UsernameToken&gt;
          &lt;wss:Username&gt;username&lt;/wss:Username&gt;
          &lt;wss:Password&gt;password&lt;/wss:Password&gt;
        &lt;/wss:UsernameToken&gt;
      &lt;/wss:Security&gt;
    &lt;/soapenv:Header&gt;
    &lt;soapenv:Body&gt;
      {snipped}
    &lt;/soapenv:Body&gt;
  &lt;/soapenv:Envelope&gt;
  </code></pre>
  
  <p>and the response we are returning looks like this...</p>
  
  <pre><code>&lt;s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:u="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"&gt;
    &lt;s:Header&gt;
      &lt;o:Security s:mustUnderstand="1" xmlns:o="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"&gt;
        &lt;u:Timestamp u:Id="_0"&gt;
          &lt;u:Created&gt;2012-05-02T01:23:12.711Z&lt;/u:Created&gt;
          &lt;u:Expires&gt;2012-05-02T01:28:12.711Z&lt;/u:Expires&gt;
        &lt;/u:Timestamp&gt;
      &lt;/o:Security&gt;
    &lt;/s:Header&gt;
    &lt;s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"&gt;
      {snipped}
    &lt;/s:Body&gt;
  &lt;/s:Envelope&gt;
  </code></pre>
  
  <p>The problem is the s:mustUnderstand="1" attribute in the response. This is causing a "Must Understand check failed" error in the Java/Axis client.</p>
  
  <p>Does anyone know how to configure WCF to remove this s:mustUnderstand attribute or at least set it to "0" instead of "1"?</p>