function staffel(a) {
	hideall();
	document.getElementById(a).style.visibility = 'visible';
}

function createXMLHttpReqObj() {  //erzeugt die XMLHttpRequest Objekte
 
    // für Mozilla etc.
    if(window.XMLHttpRequest) {
    	try {  //Fehler abfangen
			req = new XMLHttpRequest(); 
        } catch(e) {
			req = false;
        }
    // für den InternetExplorer
    } else if(window.ActiveXObject) {
       	try {
        	req = new ActiveXObject("Msxml2.XMLHTTP");
      	} catch(e) {
        	try {
          		req = new ActiveXObject("Microsoft.XMLHTTP");
        	} catch(e) {
          		req = false;
        	}
		}
	}
	return req;
}