var Viewer = null;

function HelpWindow(URL) {
         if (Viewer != null) {
            Viewer=null;
         }
                
        Viewer=window.open(URL,'helpViewer','height=350,width=400,toolbar=no,scrollbars=yes,location=no,directories=no,resizable=yes,copyhistory=no');
      Viewer.focus();
return false;
}