      *  fields listed in the fields property result in an indeterminate or
      *  non-unique sort order; that is, if two or more items have identical
      *  sort field values. An error is thrown if the sort is not unique.
+     *  The sorting logic uses this <code>unique</code> property value only if sort
+     *  field(s) are specified explicitly. If no sort fields are specified
+     *  explicitly, no error is thrown even when there are identical value
+     *  elements.
      *
      *  @default false
      *

     *
     *  </code></pre>
     *
     *  <p>This function must return the following
     *  <ul>
     *        <li>-1, if <code>a</code> should appear before <code>b</code> in
     *        the sorted sequence</li>
     *        <li>0, if <code>a</code> equals <code>b</code></li>
     *        <li>1, if <code>a</code> should appear after <code>b</code> in the
     *        sorted sequence</li>
     *  </ul></p>
     *  <p>To return to the internal comparision function set this value to
     *  <code>null</code>.</p>
     *  <p>
     *  The <code>fields</code> array specifies the object fields
     *  to compare.
     *  Typically the algorithm will compare properties until the field list is
     *  exhausted or a non zero value can be returned.
     *  For example:</p>
     *
     *  <pre><code>

     *  The method used to compare items when sorting.
     *  If you specify this property, Flex ignores any 
     *  <code>compareFunction</code> properties that you specify in the 
     *  <code>ISortField</code> objects that you use in this class.
     *
     *  <p>The compare function must have the following signature:</p>
     *
