function popupWin(URL) {

	ancho = 770
	alto = 250
	l = (screen.width/2) - (ancho/2)
	t = (screen.height/2) - (alto/2)
	params = "resizable=yes,scrollbars=yes,width=" + ancho + ",height=" + alto + ",top=" + t + ",left=" + l;
	ventana = window.open(URL,null,params);
}