title: Difference of mixed="true" and xs:extension in XML Schema
body: <p>What is the practical diference between these two:</p>
  
  <pre><code>&lt;xs:element name="A"&gt;
   &lt;xs:complexType mixed="true"&gt;
    &lt;xs:attribute name="att" type="xs:boolean"/&gt;
   &lt;/xs:complexType&gt;
  &lt;/xs:element&gt;
  
  &lt;xs:element name="B"&gt;
   &lt;xs:complexType&gt;
    &lt;xs:simpleContent&gt;
     &lt;xs:extension base="xs:string"&gt;
      &lt;xs:attribute name="att" type="xs:boolean"/&gt;
     &lt;/xs:extension&gt;
    &lt;/xs:simpleContent&gt;
   &lt;/xs:complexType&gt;
  &lt;/xs:element&gt;
  </code></pre>