function browserType(){
  if (document.layers){
    return "n4";
  }  
  if (document.all){
    return "ie";
  }
  if (!document.all && document.getElementById){
    return "n6";
  }
}
function showLayer(layerId){
  testBrowser: switch (browserType()){
  case "n4":
    document.layers[layerId].visibility = "show";
    break testBrowser;   
  case "n6":
    document.getElementById(layerId).style.visibility="visible";
    break testBrowser;  
  case "ie":
   document.getElementById(layerId).style.visibility="visible";
  }
}
function hideLayer(layerId){
testBrowser2:  switch (browserType()){
  case "n4":
    document.layers[layerId].visibility="hide";
    break testBrowser2;  
  case "n6":
    document.getElementById(layerId).style.visibility="hidden";
    break testBrowser2;  
  case "ie":
    document.getElementById(layerId).style.visibility="hidden";
  }
}