if (document.images) {
  var nav01on = new Image()
  nav01on.src = "images/menu/bt_menu01_on.gif"
  var nav01off = new Image()
  nav01off.src = "images/menu/bt_menu01_off.gif"
  
  var nav02on = new Image()
  nav02on.src = "images/menu/bt_menu02_on.gif"
  var nav02off = new Image()
  nav02off.src = "images/menu/bt_menu02_off.gif"
  
  var nav03on = new Image()
  nav03on.src = "images/menu/bt_menu03_on.gif"
  var nav03off = new Image()
  nav03off.src = "images/menu/bt_menu03_off.gif"

  var nav04on = new Image()
  nav04on.src = "images/menu/bt_menu04_on.gif"
  var nav04off = new Image()
  nav04off.src = "images/menu/bt_menu04_off.gif"

  var nav05on = new Image()
  nav05on.src = "images/menu/bt_menu05_on.gif"
  var nav05off = new Image()
  nav05off.src = "images/menu/bt_menu05_off.gif"

  var nav06on = new Image()
  nav06on.src = "images/menu/bt_menu06b_on.gif"
  var nav06off = new Image()
  nav06off.src = "images/menu/bt_menu06b_off.gif"

   var nav07on = new Image()
  nav07on.src = "images/menu/bt_menu07_on.gif"
  var nav07off = new Image()
  nav07off.src = "images/menu/bt_menu07_off.gif"
 
   var nav08on = new Image()
  nav08on.src = "images/menu/bt_menu08_on.gif"
  var nav08off = new Image()
  nav08off.src = "images/menu/bt_menu08_off.gif"
  
  var nav09on = new Image()
  nav09on.src = "images/menu/bt_menu09_on.gif"
  var nav09off = new Image()
  nav09off.src = "images/menu/bt_menu09_off.gif"
  
  var nav10on = new Image()
  nav10on.src = "images/menu/bt_menu10_on.gif"
  var nav10off = new Image()
  nav10off.src = "images/menu/bt_menu10_off.gif"

  var nav11on = new Image()
  nav11on.src = "images/menu/bt_menu11_on.gif"
  var nav11off = new Image()
  nav11off.src = "images/menu/bt_menu11_off.gif"

  var nav12on = new Image()
  nav12on.src = "images/menu/bt_menu12_on.gif"
  var nav12off = new Image()
  nav12off.src = "images/menu/bt_menu12_off.gif"

  var nav13on = new Image()
  nav13on.src = "images/menu/bt_menu13_on.gif"
  var nav13off = new Image()
  nav13off.src = "images/menu/bt_menu13_off.gif"

  var nav14on = new Image()
  nav14on.src = "images/menu/bt_menu14_on.gif"
  var nav14off = new Image()
  nav14off.src = "images/menu/bt_menu14_off.gif"
  
  var nav15on = new Image()
  nav15on.src = "images/menu/bt_menu15_on.gif"
  var nav15off = new Image()
  nav15off.src = "images/menu/bt_menu15_off.gif"
  
  var nav16on = new Image()
  nav16on.src = "images/menu/bt_menu16_on.gif"
  var nav16off = new Image()
  nav16off.src = "images/menu/bt_menu16_off.gif"

  var mapaon = new Image()
  mapaon.src = "images/contact_bt01_on.gif"
  var mapaoff = new Image()
  mapaoff.src = "images/contact_bt01_off.gif"

  var mapbon = new Image()
  mapbon.src = "images/contact_bt02_on.gif"
  var mapboff = new Image()
  mapboff.src = "images/contact_bt02_off.gif"
}
function inact(imgName) {
  if (document.images)
    document[imgName].src = eval(imgName + 'off.src');
}

function act(imgName) {
  if (document.images)
    document[imgName].src = eval(imgName + 'on.src');
}