function getBrowserType() {
	if (document.getElementById) return 'dom';
	if (document.all) return 'ie4';
	if (document.layers) return 'nn4';
	return false;
}
bt = getBrowserType();
function getLayer(lname) {
	if (bt == 'dom') return document.getElementById(lname);
	if (bt == 'ie4') return document.all[lname];
	if (bt == 'nn4') return document.layers[lname];
	return false;
}
function getLayerProp(lname) {
	l = getLayer(lname);
	if (bt == false) {
		return false;
	} else if (bt == 'nn4') {
		return l;
	} else {
		return l.style;
	}
}
function isShown(lname) {
	pl = getLayerProp(lname);
	if (pl.visibility == 'hidden') return false;
	return true;
}
function showLayer(lname) {
	pl = getLayerProp(lname);
	if (bt == 'dom') pl.display = 'inline';
	pl.visibility = '';
} 
function hideLayer(lname) {
	pl = getLayerProp(lname);
	pl.visibility = 'hidden';
	if (bt == 'dom') pl.display = 'none';
}
function switchLayer(lname) {
	pl = getLayerProp(lname);
	if (pl.visibility == 'hidden') {
		if (bt == 'dom') pl.display = 'inline';
		pl.visibility = '';
	} else {
		pl.visibility = 'hidden';
		if (bt == 'dom') pl.display = 'none';
	}
}