Browser = false ;
if (((navigator.appName.charAt(0)=="N") && (navigator.appVersion.charAt(0)>=3)) || ((navigator.appName.charAt(0)=="M") && (navigator.appVersion.charAt(0)>=4))) {
    Browser = true;

    		b1on = new Image(); b1on.src = "img/b1-on.gif";
			b1off = new Image(); b1off.src = "img/b1-off.gif";
			b2on = new Image(); b2on.src = "img/b2-on.gif";
			b2off = new Image(); b2off.src = "img/b2-off.gif";
			b3on = new Image(); b3on.src = "img/b3-on.gif";
			b3off = new Image(); b3off.src = "img/b3-off.gif";
			b4on = new Image(); b4on.src = "img/b4-on.gif";
			b4off = new Image(); b4off.src = "img/b4-off.gif";
			b5on = new Image(); b5on.src = "img/b5-on.gif";
			b5off = new Image(); b5off.src = "img/b5-off.gif";
			b6on = new Image(); b6on.src = "img/b6-on.gif";
			b6off = new Image(); b6off.src = "img/b6-off.gif";  
    
    }

function turnon(which) {
    if (Browser == true) { document[which].src =eval(which + "on.src"); }
}

function turnoff(which) {
    if (Browser == true) { document[which].src =eval(which + "off.src"); }
}