 <!--
if (document.images) {
    button_1up       = new Image();
    button_1up.src   = "images/button_1_off.gif" ;
    button_1down     = new Image() ;
    button_1down.src = "images/button_1_on.gif" ;
   
    button_2up       = new Image();
    button_2up.src   = "images/button_2_off.gif" ;
    button_2down     = new Image() ;
    button_2down.src = "images/button_2_on.gif" ;

    button_3up       = new Image();
    button_3up.src   = "images/button_3_off.gif" ;
    button_3down     = new Image() ;
    button_3down.src = "images/button_3_on.gif" ; 
	
	button_4up       = new Image();
    button_4up.src   = "images/button_4_off.gif" ;
    button_4down     = new Image() ;
    button_4down.src = "images/button_4_on.gif" ; 
	
}
function buttondown( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "down.src" );
    }
}
function buttonup ( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "up.src" );
    }
}
// -->