aa1=new Image(45,45)
	aa1.src="images/nav-port1off.gif"
	aa2=new Image(45,45)
	aa2.src="images/nav-port1on.gif"
	
	bb1=new Image(45,45)
	bb1.src="images/nav-port2off.gif"
	bb2=new Image(45,45)
	bb2.src="images/nav-port2on.gif"
	
	cc1=new Image(45,45)
	cc1.src="images/nav-port3off.gif"
	cc2=new Image(45,45)
	cc2.src="images/nav-port3on.gif"
	
	function filter(imagename,objectsrc){
	if (document.images)
	document.images[imagename].src=eval(objectsrc+".src")
	}