nn4=(document.layers)?true:false;
ie4=(document.all)?true:false;
nonmac=(navigator.appVersion.indexOf("Macintosh")==-1);
ie4=ie4 && nonmac;

function show(ident) {
  if(nn4) {  
  document.layers[ident].visibility = "show";
  } else if(ie4) {  
    document.all[ident].style.visibility = "visible";
  }
}

function hide(ident) {
  if(nn4) {  
 document.layers[ident].visibility = "hide";
  } else if(ie4) {
    document.all[ident].style.visibility = "hidden";
  }
}