title: Is xmlns="" a valid xml namespace?
body: <p>Is "empty" a valid value for XML namespace? If yes what does it mean?</p>
  
  <p>I have the following XML code but I'm not sure to which namespace <code>Field1</code> and <code>Field2</code> elements belong to.</p>
  
  <pre><code>&lt;soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"&gt;
    &lt;soapenv:Header /&gt;
    &lt;soap:Body&gt;
      &lt;Root xmlns="uri"&gt;
        &lt;Field1 xmlns=""&gt;147079737&lt;/Field1&gt;
        &lt;Field2 xmlns=""&gt;POL&lt;/Field2&gt;
      &lt;/Root&gt;
    &lt;/soap:Body&gt;
  &lt;/soapenv:Envelope&gt;
  </code></pre>