function div_ref_style (id) {
	if      (document.layers)         return document.layers[id];              
	else if (document.all)            return document.all[id].style;           
	else if (document.getElementById) return document.getElementById(id).style;
	else                              return null;        
}

function show_hide (id,stat) {
	div_ref_style(id).display =  stat? "block" : "none";
}