ban_img = new  Array("banner1.gif","banner6.gif","banner3.gif","banner4.gif","banner5.gif","banner2.gif");
ban_url = new Array("#","clamping_eng.htm","#","#","#","#");
a = Math.floor((ban_img.length - 1) * Math.random());
//a = 5;
url_uno = "<A HREF=\"" + ban_url[a] + "\"><IMG SRC=\"img/" + ban_img[a] + "\" WIDTH=470 HEIGHT=62 BORDER=0></A>";