function ShowSubMenu(x)
{
  for (i=1;i<=4;i++)
  {
    if (document.all['SubMenu'+i]!=null)
    {
      if (i==x)
      {
        document.all['SubMenu'+i].style.display="block";
      }
      else
      {
        document.all['SubMenu'+i].style.display="none";
      }
    }
  }
}