var BuchungsFenster = null;
function go() {
        if ( BuchungsFenster == null ) {
                BuchungsFenster = window.open("", "Buchungsanfrage", "toolbar=no,width=750,height=550,directories=no,status=yes,scrollbars=yes,resize=yes,menubar=no" );
        } else {
                if ( BuchungsFenster.closed )
                        BuchungsFenster = window.open("", "Buchungsanfrage", "toolbar=no,width=750,height=550,directories=no,status=yes,scrollbars=yes,resize=yes,menubar=no" );
                else
                        BuchungsFenster.focus();
        }

document.bkrequest.target="Buchungsanfrage";
document.bkrequest.action="http://www.hoteldaten.com/koop-apis/wdba/dorequest.php";
document.bkrequest.submit();
document.bkrequest.action="go()";
document.bkrequest.target="_self";
}