if (document.images) {         
            img1on = new Image();      
            img1on.src = "i/img1_on.gif";
            
            img2on = new Image();      
            img2on.src = "i/img2_on.gif";
            
            img3on = new Image();      
            img3on.src = "i/img3_on.gif";
            
            img4on = new Image();      
            img4on.src = "i/img4_on.gif";
            
            img5on = new Image();      
            img5on.src = "i/img5_on.gif";
            
            img6on = new Image();      
            img6on.src = "i/img6_on.gif";
            
            img7on = new Image();      
            img7on.src = "i/img7_on.gif";

            img1off = new Image(); 
            img1off.src = "i/img1_off.gif"; 
            
            img2off = new Image(); 
            img2off.src = "i/img2_off.gif"; 
            
            img3off = new Image(); 
            img3off.src = "i/img3_off.gif"; 
            
            img4off = new Image(); 
            img4off.src = "i/img4_off.gif"; 
            
            img5off = new Image(); 
            img5off.src = "i/img5_off.gif"; 
            
            img6off = new Image(); 
            img6off.src = "i/img6_off.gif"; 
            
            img7off = new Image(); 
            img7off.src = "i/img7_off.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");
        }
}