title: cts:field-value-query to compare date
body: <pre><code>&lt;entry&gt;
    &lt;date&gt;1971-12-23&lt;/date&gt;
     &lt;info&gt;Some different information.&lt;/info&gt;
  &lt;/entry&gt; 
  
  cts:search(doc("/dates.xml")/root/entry, 
    cts:element-range-query(xs:QName("date"), "&lt;=",xs:date("2000-01-01") ) )
  </code></pre>
  
  <p>If I have a field <code>rpdt</code>, how would I construct cts:field-word-query to compare date? I got an error code.</p>
  
  <pre><code>cts:field-word-query("rpdt", "&lt;=", xs:date("1952-03-15"))
  </code></pre>