function login(){
      f = document.forms['fLogin'];
      f.action='http://metric.certifica.com/Login_ok.php';
      f.method='POST';
      _u=f.elements['userName'].value;_p=f.elements['passwd'].value;
      f.submit();
   }
   
   function ve(e){
      if (window.event) _k=e.keyCode;
      else _k=e.which;
      if (_k==13) login();
   }

   function muestraLogin(){
      caja = document.getElementById("Log_in_form");
      if (caja.style.visibility=='hidden') caja.style.visibility='visible'; 
      else caja.style.visibility='hidden';
   }