function toggleDIV ( whichDIV )
{
  var elem;
  if( document.getElementById )
    elem = document.getElementById( whichDIV );
  else if( document.all ) // Supposedly for old MSIE versions
    elem = document.all[whichDIV];
  else if( document.layers ) // Supposedly for Netscape 4
    elem = document.layers[whichDIV];
  if( elem.className=='hidden' )
    elem.className = 'visible';
  else if( elem.className=='visible' )
    elem.className = 'hidden';
}