dom = (document.getElementById)? true : false;
nn4 = (document.layers)? true : false;
ie4 = (document.all && !dom)? true : false;

function showPage(pageAddress) { 
document.getElementById('pageframe').innerHTML='<iframe src="'+pageAddress+'" width="100%" height="100%" scrolling="no" frameborder="0">'; 
document.getElementById('pageframe').style.display = "block"; 
} 
function hidePage() {  
if (dom) document.getElementById('pageframe').style.display = "none";}