if (document.images) {
          menu1 = new Image();
          menu1.src="images/menu_hover_cctv.gif";
          menu2 = new Image();
          menu2.src="images/menu_hover_autogate.gif";
          menu3 = new Image();
          menu3.src="images/menu_hover_barrier.gif";
          menu4 = new Image();
          menu4.src="images/menu_hover_door_access.gif";
          menu5 = new Image();
          menu5.src="images/menu_hover_alarm.gif";
          menu6 = new Image();
          menu6.src="images/menu_hover_keyphone.gif";

          menu_off1 = new Image();
          menu_off1.src="images/menu_cctv.gif";
          menu_off2 = new Image();
          menu_off2.src="images/menu_autogate.gif";
          menu_off3 = new Image();
          menu_off3.src="images/menu_barrier.gif";
          menu_off4 = new Image();
          menu_off4.src="images/menu_door_access.gif";
          menu_off5 = new Image();
          menu_off5.src="images/menu_alarm.gif";
          menu_off6 = new Image();
          menu_off6.src="images/menu_keyphone.gif";
     }
     function chgIMG(picName,imgName) {
          if (document.images) {
              imgOn=eval(imgName + ".src");
              document[picName].src= imgOn;
          }
     }