if (document.images) {
     A1=new Image();
     A2=new Image();
     A1.src="back1.gif";
     A2.src="back2.gif";
     B1=new Image();
     B2=new Image();
     B1.src="top1.gif";
     B2.src="top2.gif";
     C1=new Image();
     C2=new Image();
     C1.src="next1.gif";
     C2.src="next2.gif";
   }