title: Matching values to element names in XML Schema
body: <p>Is it possible to validate attribute values against element names in an XmlSchema.
  For e.g. For the XML fragment below, I want to ensure that the value in the <strong>'thisShouldBeAnElementName'</strong> attribute should be an element name. So, valid values would be 'a','b' or 'c'.</p>
  
  <pre><code>&lt;root&gt;
    &lt;a/&gt;
    &lt;b/&gt;
    &lt;c thisShouldBeAnElementName='a'/&gt;
  &lt;/root&gt;
  </code></pre>
  
  <p>Thanks.</p>