title: validate order attribute in xsd for xml file
body: <p>I have a problem in xsd, i dont know why stackoverflow is preventing me from asking.
  I want to have a tag that looks like this</p>
  
  <pre><code>      &lt;tag order="1"&gt;
        &lt;something&gt;something&lt;/something&gt;
        &lt;/tag&gt;
  </code></pre>
  
  <p>but i also want to validate this using validation.</p>
  
  <p>in xsd, i have</p>
  
  <pre><code>&lt;xsd:element name="tag"&gt;
  &lt;xsd:complexType&gt;
  &lt;xsd:sequence&gt;
  &lt;xsd:element name="something"&gt;
  &lt;xsd:sequence&gt;
  &lt;xsd:complexType&gt;
  </code></pre>
  
  <p>i can individually pass syntax test but when i put both validation and the xml file together, i kept getting errors that say order attribute is not allowed to appear in this tag. 
  I want to use this order attribute because it is required. If anyone can kindly let me know how! Much appreciate!</p>