function vermarcas(categoria) {
	var req = generar_ajax();
	var url="/publicar/selectmarca.asp?categoria="+ escape(categoria);
	req.onreadystatechange= function () {
		if (req.readyState != 4) {
    		return;
  		}
  		if (req.status == 200) {
    		document.getElementById("marcas").innerHTML=req.responseText;	    		
  		} 
  		else { alert("Error");}
		req = null;
	}
	req.open("POST", url, true);
	var encoded = "";
	encoded = "categoria="+ escape(categoria);
	req.send(encoded);
}


function vermodelos(categoria,marca,idmodelo) {
	var req = generar_ajax();
	var url="/publicar/selectmodelo.asp?categoria="+ escape(categoria) + "&marca="+ escape(marca) + "&idmodelo="+ escape(idmodelo);
	req.onreadystatechange= function () {
		if (req.readyState != 4) {
    		return;
  		}
  		if (req.status == 200) {
    		document.getElementById("marcas").innerHTML=req.responseText;	    		
  		} 
  		else { alert("Error");}
		req = null;
	}
	req.open("POST", url, true);
	var encoded = "";
	encoded = "categoria="+ escape(categoria) + "&marca="+ escape(marca) + "&idmodelo="+ escape(idmodelo);
	req.send(encoded);
}

function generar_ajax () {
	var req = false;
	if (window.XMLHttpRequest) {
		try {
			req = new XMLHttpRequest();
		} catch (e) {
			req = false;
		}
	} 
	else if (window.ActiveXObject) {
		try {
			req = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				req = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {
				req = false;
			}
		}
	}
	return req;
}