function updateTag(url, param, target, funcRec) {
    new Ajax.Request(url, { method:'post',
        asynchronous: true,
        parameters: param,
        onComplete: function(xmlHttpRequest) {
            updateTagDone(xmlHttpRequest, target, funcRec);
        }
    });
}

function updateTagDone(_req, target, funcRec) {
    if (_req.readyState == 4) {
        if (_req.status == 200) {
                $(target).innerHTML = _req.responseText;
                if (funcRec) funcRec(_req);
            } else {
                $(target).innerHTML = "Errore: " + _req.statusText;
        }
    }
    return false;
}