{
        if( !(isset($args['ref']))) return "<span style='color:red;'>@reference missing</span>";
        if( !(isset($args['start']))) return "<span style='color:red;'>@start missing</span>";
        if( !(isset($args['end']))) return "<span style='color:red;'>@end missing</span>";
        $ref=trim($args['ref']);
        if(strlen($ref)==0)  return "<span style='color:red;'>bad @reference</span>";
        $start=(int)trim(str_replace(',','',$args['start']));
        $end=(int)trim(str_replace(',','',$args['end']));
        if(!is_int($start)) return      "<span style='color:red;'>bad @start</span>";
        if(!is_int($end)) return        "<span style='color:red;'>bad @end</span>";
        $url="http://www.myip.com/cgi-bin/gbrowse/buildname/?name=".
                $ref."%3A".$start."..".$end;

        $html=  "<div style='text-align:center;margin:10pt;'>".
                "<a href='".$url."' target='_blank'>".$chrom.":".$start."-".$end."</a><br/>".
                "<iframe height='".(isset($args['height'])?$args['height']:"500px")."' width='90%' src ='".$url."' />".
                "</iframe></div>"
                ;
        return $html;
        }