var visibleVar="null"; 
function init(){
if (navigator.appName == "Netscape") {
layerRef="document.layers"; 
styleSwitch=""; 
visibleVar="show";
}else{
layerRef="document.all"; 
styleSwitch=".style"; 
visibleVar="visible";
}
} 
function showHideLayerSwitch(layerName){
if (eval(layerRef+'["'+layerName+'"]'+styleSwitch+'.visibility == visibleVar')){ 
hideLayer(layerName); 
}else{ 
showLayer(layerName); 
}
} 
function showLayer(layerName){
eval(layerRef+'["'+layerName+'"]'+styleSwitch+'.visibility="visible"');
} 
function hideLayer(layerName){
eval(layerRef+'["'+layerName+'"]'+styleSwitch+'.visibility="hidden"');
}