title: logical XOR operator in Progress
body: <p>Is there <code>XOR</code> operator in Progress?<br>
  There is <code>AND</code>, <code>OR</code> and <code>NOT</code>, so, i can code "<code>XOR</code>" like this:</p>
  
  <pre><code>(a OR b) AND NOT (a AND b)
  </code></pre>
  
  <p>I just want to know if the operator exists (with another name).</p>
  
  <p>Thanks.</p>