function mostrar(nombreCapa){
document.getElementById(nombreCapa).style.visibility="visible";
}
function ocultar(nombreCapa){
document.getElementById(nombreCapa).style.visibility="hidden";
}
function finestra (URL){ 
   window.open(URL,"ventana1","width=748,height=700,toolbar=no,menubar=no,location=no,status=no,scrollbars=no,resizable=no") 
} 
function finestra1 (URL){ 
   window.open(URL,"ventana2","width=460,height=350,toolbar=no,menubar=no,location=no,status=no,scrollbars=no,resizable=no") 
}