title: Choice element in XML Schema with any order, any number and "one element restriction"?
body: <p>What I'm trying to do is, declare an parent element called "data", which are having 6 sub element of these one element are conditional that means one element is appear only and only one time and other can appear any number of times with any order.</p>
  
  <pre><code>Example:
  
  &lt;data&gt;
     &lt;Child1&gt;text1&lt;/Child1&gt;
     &lt;Child2&gt;text1&lt;/Child2&gt;
     &lt;Child3&gt;text1&lt;/Child3&gt;
     &lt;Child4&gt;text1&lt;/Child4&gt;
     &lt;Child5&gt;text1&lt;/Child5&gt;
     &lt;Child6&gt;text1&lt;/Child6&gt; &lt;!-- Only one times--&gt;
  
  
  &lt;/data&gt;
  </code></pre>
  
  <p>1 : All element can appear in any order and any number of times.</p>
  
  <p>2 : Child6 is appear only one time.</p>
  
  <p><strong>XSD Code</strong></p>
  
  <pre><code>&lt;xs:element name="data"&gt;
          &lt;xs:complexType&gt;
              &lt;xs:sequence&gt;
                  &lt;xs:element name="sequence" minOccurs="0" maxOccurs="unbounded"&gt;
                      &lt;xs:complexType&gt;
                          &lt;xs:choice minOccurs="0" maxOccurs="unbounded" &gt;
                              &lt;xs:element ref="Child1" /&gt;
                              &lt;xs:element ref="Child1" /&gt;
                              &lt;xs:element ref="Child3" /&gt;
                              &lt;xs:element ref="Child4" /&gt;                          
                              &lt;xs:element ref="Child5" /&gt;
                              &lt;xs:element ref="Child6" minOccurs="0" maxOccurs="1"/&gt;
  
                          &lt;/xs:choice&gt;
                      &lt;/xs:complexType&gt;
                  &lt;/xs:element&gt;
              &lt;/xs:sequence&gt;
          &lt;/xs:complexType&gt;
      &lt;/xs:element&gt;
  </code></pre>
  
  <p>Please suggest me how can i do it.?</p>