function popup(url) {
   var option = "top=200,left=0," +
                "location=0,directories=0," +
                "status=0,toolbar=0," +
                "height=330,width=320," +
                "resizable=yes";
   url = url + "?REQ_URL=" + document.location;

   var new_win = window.open(url, "onlineHelp", option );
   if ( !new_win ) {
     alert( "Sorry, the help window is a popup window, but" +
            " we cannot open a popup window now.\n" +
            "If you use popup window blocker, please disable it so we " +
            "can help you.");
  }

}