var req;

function loadXMLDoc(url)
{
    // branch for native XMLHttpRequest object
    //if (window.XMLHttpRequest) {
    if(window.XMLHttpRequest && !(window.ActiveXObject)) {
			try {
				req = new XMLHttpRequest();
      } catch(e) {
				req = false;
      }
    // branch for IE/Windows ActiveX version
    } else if (window.ActiveXObject) {
        try {
        	req = new ActiveXObject("Msxml2.XMLHTTP");
      	} catch(e) {
        	try {
          		req = new ActiveXObject("Microsoft.XMLHTTP");
        	} catch(e) {
          		req = false;
        	}
		    }
		  }
       if (req) {
           req.onreadystatechange = processReqChange;
           req.open("GET", url, true);
//						req.send(); //no funciona con Firefox
//           req.send(""); // IE ¿7?
	        req.send(null); //navegador no explorer (Firefox 2, IE6)
       }
    }



function processReqChange()
{
    // only if req shows "complete"
    if (req.readyState == 4) {
        // only if "OK"
        if (req.status == 200) {
            processResult(req);
        }
				else {
            alert(req.statusText);
						alert("Ha ocurrido un error y no se pueden cargar los datos.");
						processError();
        }
    }
}