subMenuLoaded = false;

if (document.layers) // Got Netscape <= 4
{
  visible = 'show';
  hidden = 'hide';
}
else if (document.all) // Got IE
{
  visible = 'visible';
  hidden = 'hidden';
}
else //Netscape 6
{
  visible = 'visible';
  hidden = 'hidden';
}

menuNames = new Array('understandingMenu',
					  'treatingMenu');


function menuDisp(num)
{
  if (subMenuLoaded)
  {
    for (var j=0 ; j<menuNames.length ; j++)
    {
      menu = menuNames[j];
      
      if (document.layers) // NS <= 4
      {
        myMenu = document.layers[menu];
      }
      else if (document.all) // IE
      {
        myMenu = document.all(menu).style;
      }
      else // NS 6
      {
        myMenu = document.getElementById(menu).style;
      }
  
      if (!isNaN(num))
      {
        if (menuNames[num] != menuNames[j])
        {
          myMenu.visibility = hidden;
        }
        else
        {
          myMenu.visibility = visible;
        }
      }
      else
      {
        myMenu.visibility = hidden;
      }
    }
  }
}