function vercheck(IEversion,NNversion){
n_ver = navigator.appVersion;
index1 = n_ver.indexOf("MSIE",0);
if(index1 != -1){
n_ver = n_ver.substring(index1,n_ver.length);
index2 = n_ver.indexOf(" ",0) + 1;
n_ver = n_ver.substring(index2,n_ver.length);
}
if ((navigator.appName.indexOf("Microsoft") >= 0)&& (IEversion != 0)&& (IEversion <= parseFloat(n_ver))){
return true;
} else {
if ((navigator.appName.indexOf("Netscape") >= 0)&& (NNversion != 0)&& (NNversion <= parseFloat(n_ver))){
return true;
} else {
return false;
}
}
}


function vis_lyr(slayer,ptn) {
if (vercheck(0,5)) {
document.getElementById(slayer).style.visibility = ptn;
}
else if (vercheck(0,4)) {
document.layers[slayer].visibility = ptn;
}
else {
document.all[slayer].style.visibility = ptn;
}
}


var nowlyr = 'th01';

function switchlyr(lyrname) {
	vis_lyr(nowlyr,'hidden');
	vis_lyr(lyrname,'visible');
	nowlyr = lyrname;
}