function createRequestObject() {
    var ro;
    var browser=navigator.appName;
    if(browser=="Microsoft Internet Explorer"){
        ro=new ActiveXObject("Microsoft.XMLHTTP");
    } else {
        ro=new XMLHttpRequest();
    }
    return ro;
}

ajax=createRequestObject();

function updatecombo(combo_id,param) {
 ajax.open('get','ajax.php?op=updatecombo&combo='+combo_id+'&param='+param);
 ajax.onreadystatechange=updatecombodone;
 ajax.send(null);
 selector=document.getElementById(combo_id);
}

function updatecombodone() {
 if(ajax.readyState==4) {
 	var data=ajax.responseText;
 	source = new Array;
 	thisitem = new Array;
 	combo = data.split('\n');
	for(lc=0;lc<combo.length;lc++) {
		source = combo[lc].split('^');
		if(source[0]!='') {
			selector = document.getElementById(source[0]);
			selector.length=1;
		 	for(sc=1;sc<source.length;sc++) {
		 		thisitem = source[sc].split('|');
				newoption = new Option(thisitem[1],thisitem[0],false,false);
		 		selector.options[sc] = newoption;
		 		}
		 		selector.selectedIndex=0;
			}
	 	}
	}
}