title: && in XML (logical operations)
body: <p>in an application I'm using a config-file in which i'd like also to use '&amp;&amp;'.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="ISO-8859-1" ?&gt;
  &lt;use-case id="customer"&gt;
      &lt;precondition evaluate="!empty customer &amp;&amp; !empty product" /&gt;
      &lt;menu-item id="customer" label="Kunde" /&gt;
  &lt;/use-case&gt;
  </code></pre>
  
  <p>With this code I'm getting an validation error owing to the '&amp;&amp;' ...</p>
  
  <p>Is there any solution to express this?</p>
  
  <p>THX</p>