if (document.images) { 

var img17on = new Image();
img17on.src = "../images/advert_cat_clothes_on.gif"; 
var img17off = new Image();
img17off.src = "../images/advert_cat_clothes.gif";

var img18on = new Image();
img18on.src = "../images/advert_cat_eat_on.gif"; 
var img18off = new Image();
img18off.src = "../images/advert_cat_eat.gif";

var img19on = new Image();
img19on.src = "../images/advert_cat_cafe_on.gif";
var img19off = new Image();
img19off.src = "../images/advert_cat_cafe.gif";

var img20on = new Image();
img20on.src = "../images/advert_cat_amusement_on.gif";
var img20off = new Image();
img20off.src = "../images/advert_cat_amusement.gif";

var img21on = new Image();
img21on.src = "../images/advert_cat_traffic_on.gif";
var img21off = new Image();
img21off.src = "../images/advert_cat_traffic.gif";

var img22on = new Image();
img22on.src = "../images/advert_cat_finance_on.gif";
var img22off = new Image();
img22off.src = "../images/advert_cat_finance.gif";

var img23on = new Image();
img23on.src = "../images/advert_cat_shop_on.gif";
var img23off = new Image();
img23off.src = "../images/advert_cat_shop.gif";

var img24on = new Image();
img24on.src = "../images/advert_cat_electro_on.gif";
var img24off = new Image();
img24off.src = "../images/advert_cat_electro.gif";

var img25on = new Image();
img25on.src = "../images/advert_cat_machine_on.gif";
var img25off = new Image();
img25off.src = "../images/advert_cat_machine.gif";

var img26on = new Image();
img26on.src = "../images/advert_cat_social_on.gif";
var img26off = new Image();
img26off.src = "../images/advert_cat_social.gif";

var img27on = new Image();
img27on.src = "../images/advert_cat_event_on.gif"; 
var img27off = new Image();
img27off.src = "../images/advert_cat_event.gif";

var img28on = new Image();
img28on.src = "../images/advert_cat_usa_on.gif"; 
var img28off = new Image();
img28off.src = "../images/advert_cat_usa.gif";

} 


function On(name) { 

if (document.images) { 
document.images[name].src = eval(name + 'on.src'); 
} 

} 


function Off(name) { 

if (document.images) { 
document.images[name].src = eval(name + 'off.src'); 
} 

}