var state = 'none'; 
function showhide(layer_ref){ 
if(state == 'block'){ 
state = 'none'; 
}else{ 
state = 'block'; 
} 
if(document.all){ //IS IE 4 or 5 (or 6 beta) 
eval("document.all." +layer_ref+ ".style.display = state"); 
} 
if (document.layers) { //IS NETSCAPE 4 or below 
document.layers[layer_ref].display = state; 
} 
if (document.getElementById &&!document.all) { 
hza = document.getElementById(layer_ref); 
hza.style.display = state; 
} 
}