="changed_added_2_0"><span
            class="changed_modified_2_0_rev_a">Is</span> either an EL
            expression pointing to the element in the value collection
            whose value should be marked as a &#8220;no selection&#8221;
            item, or a literal string that exactly matches the value of
            the item in the collection that must be marked as the
            &#8220;no selection&#8221; item.  If the user selects such
            an item <strong>and</strong> the field is marked a