if (document.images) {
     button00a = new Image
     button00b = new Image
     button01a = new Image
     button01b = new Image
     button02a = new Image
     button02b = new Image
     button03a = new Image
     button03b = new Image
     button04a = new Image
     button04b = new Image

     button00a.src = 'images/adsl00a.gif'
     button00b.src = 'images/adsl00b.gif'
     button01a.src = 'images/adsl01a.gif'
     button01b.src = 'images/adsl01b.gif'
     button02a.src = 'images/adsl02a.gif'
     button02b.src = 'images/adsl02b.gif'
     button03a.src = 'images/adsl03a.gif'
     button03b.src = 'images/adsl03b.gif'
     button04a.src = 'images/adsl04a.gif'
     button04b.src = 'images/adsl04b.gif'
 }