function submenu( menu )
{
 var bullet = document.all( menu.id + "-bullet" );
 if( menu.style.display == "none" )
 {
  menu.style.display = "";
  bullet.src = "images/minus.gif";
 }
 else
 {
  menu.style.display = "none";
  bullet.src = "images/plus.gif";
 }
}