if (document.images) {            
            img1on = new Image();   img1on.src = "images/inv_b1a.gif"; 
            img2on = new Image();   img2on.src = "images/inv_b2a.gif";
            img3on = new Image();   img3on.src = "images/inv_b3a.gif";  
            img4on = new Image();   img4on.src = "images/inv_b4a.gif";  
            img5on = new Image();   img5on.src = "images/inv_b5a.gif";  
            img6on = new Image();   img6on.src = "images/inv_b6a.gif";  
            img7on = new Image();   img7on.src = "images/inv_b7a.gif";  
            img8on = new Image();   img8on.src = "images/inv_b5a.gif";  
            img9on = new Image();   img9on.src = "images/inv_b6a.gif";  
            img10on = new Image();  img10on.src = "images/inv_b5a.gif";  
            img11on = new Image();  img11on.src = "images/inv_b7a.gif";  
            img12on = new Image();  img12on.src = "images/inv_b7a.gif";  
            img13on = new Image();  img13on.src = "images/inv_b8a.gif";  
            img14on = new Image();  img14on.src = "images/inv_b9a.gif"; 
		    img15on = new Image();  img15on.src = "images/inv_b10a.gif"; 
			img16on = new Image();  img16on.src = "images/inv_b11a.gif";
            

            img1off = new Image();  img1off.src = "images/inv_b1.gif";
            img2off = new Image();  img2off.src = "images/inv_b2.gif";
            img3off = new Image();  img3off.src = "images/inv_b3.gif";
            img4off = new Image();  img4off.src = "images/inv_b4.gif";
            img5off = new Image();  img5off.src = "images/inv_b5.gif";
            img6off = new Image();  img6off.src = "images/inv_b6.gif";
            img7off = new Image();  img7off.src = "images/inv_b7.gif";
            img8off = new Image();  img8off.src = "images/inv_b5.gif";  
            img9off = new Image();  img9off.src = "images/inv_b6.gif";  
            img10off = new Image(); img10off.src = "images/inv_b5.gif";  
            img11off = new Image(); img11off.src = "images/inv_b7.gif";  
            img12off = new Image(); img12off.src = "images/inv_b7.gif";  
            img13off = new Image(); img13off.src = "images/inv_b8.gif";  
            img14off = new Image(); img14off.src = "images/inv_b9.gif";
			img15off = new Image(); img15off.src = "images/inv_b10.gif";
			img16off = new Image(); img16off.src = "images/inv_b11.gif";
      }

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

    function imgOff(imgName) {
            if (document.images) {
                document[imgName].src = eval(imgName + "off.src");        
            }
    }