var http_request = false;

    function ortplz(url) {

var pol = document.forms.formular.plz.value;

var urli = url + '?plz=' + pol;

if (pol.length < 4)
{ document.getElementById('display').style.display = "none"; }
else {
        //ajax-loader
        displayanzeigen();

        http_request = false;

        if (window.XMLHttpRequest) { // Mozilla, Safari,...
            http_request = new XMLHttpRequest();
            if (http_request.overrideMimeType) {
                http_request.overrideMimeType('text/xml');
                // zu dieser Zeile siehe weiter unten
            }
        } else if (window.ActiveXObject) { // IE
            try {
                http_request = new ActiveXObject("Msxml2.XMLHTTP");
            } catch (e) {
                try {
                    http_request = new ActiveXObject("Microsoft.XMLHTTP");
                } catch (e) {}
            }
        }

        if (!http_request) {
            alert('Ende :( Kann keine XMLHTTP-Instanz erzeugen');
            return false;
        }
        http_request.onreadystatechange = alertInhalt;
        http_request.open('GET', urli, true);
        http_request.send(null);

    }

    function alertInhalt() {

        if (http_request.readyState == 4) {
            if (http_request.status == 200) {

                var xmldoc = http_request.responseXML;
                if (xmldoc.getElementsByTagName('ort').length > 1) {
                        var fuellung = "Bitte Ort auswhlen:<br>";
                        for (var i=0; i < xmldoc.getElementsByTagName('ort').length; ++i) {
                        wert = xmldoc.getElementsByTagName('ort')[i].firstChild.data;
                        fuellung = fuellung+"<a href=\"#\" onclick=\"fuellen('"+wert+"')\">"+wert+"</a><br>\n";
                        document.getElementById('display').innerHTML = fuellung;
                        displayanzeigen();
                        }
                }
                else {
                        //ajax-loader ausschalten
                        document.getElementById('display').style.display = "none";
                        document.forms.formular.city.value = xmldoc.getElementsByTagName('ort').item(0).firstChild.data;
                }

                        document.forms.formular.telephone_city.value = xmldoc.getElementsByTagName('vorwahl_city').item(0).firstChild.data;
                        document.forms.formular.fax_city.value = xmldoc.getElementsByTagName('vorwahl1').item(0).firstChild.data;


            } else {
                alert('Bei dem Request ist ein Problem aufgetreten.');
            }
        }


}
    }

      function fuellen(fuellvar)    {
      document.formular.city.value = fuellvar;
      document.getElementById('display').style.display = "none";
      }

      function displayanzeigen()    {
        document.getElementById('display').style.display = "block";
      }

      function displayaendern()    {
        document.getElementById('display').innerHTML ="<a href=\"#\" onclick=\"fuellen('Free')\">Free</a><br>";
      }