<!-- script to handle IE4/5 document.all when getElementById is not available.  Not catering for NN4 document.layers -->
if(document.all && !document.getElementById) {
	
    document.getElementById = function(id) {
         return document.all[id];
    }
}
<!-- Now we have the functions -->

function show(tact,act) {
	for (ct = 1; ct < tact+1; ct++)  {
	
	document.getElementById('desc'+ct).style.visibility='hidden';
	
	}
	
    desclay="desc" + act;
	

	document.getElementById(desclay).style.visibility='visible';
	
	
	
	}