function ValidarLogin(obj)
{
  num="01213456789abcdefghijklmnopqrstuwyxzABCDEFGHIJKLMNOPQRSTUWYVXZ";
  v=obj.value;
  for(i = 0; i <= v.length-1; i++)
  {
    f = i + 1;
    s = v.substring(i, f);
    if (num.indexOf(s) < 0)
    {
      obj.value = obj.value.substring(0,i);
      obj.focus();
      return false;
    }
  }
  return true;
}

function ValidarNumerico(obj,campo)
{
  num="01213456789";
  v=obj.value;
  for(i = 0; i <= v.length-1; i++)
  {
    f = i + 1;
    s = v.substring(i, f);
    if (num.indexOf(s) < 0)
    {
      obj.value = obj.value.substring(0,i);
      obj.focus();
      return false;
    }
  }
  if(campo!=null)
  {
    if(obj.value.length == obj.getAttribute('maxlength'))
    {
      campo.focus();
    }
  }
  return true;
}