if (document.images) {	

   	sub_index1_on = new Image();				sub_index1_on.src="images/navigation/sub_index1b.gif";  
	sub_index1_off = new Image();		 		sub_index1_off.src="images/navigation/sub_index1a.gif";  
	
   	sub_index2_on = new Image();				sub_index2_on.src="images/navigation/sub_index2b.gif";  
	sub_index2_off = new Image();		 		sub_index2_off.src="images/navigation/sub_index2a.gif";  	
	
   	sub_index3_on = new Image();				sub_index3_on.src="images/navigation/sub_index3b.gif";  
	sub_index3_off = new Image();		 		sub_index3_off.src="images/navigation/sub_index3a.gif";  	
		
}