function optionalToggle() {
	t = document.getElementById('special');
	ths = t.getElementsByTagName('th');
	tds = t.getElementsByTagName('td');
	display = (navigator.appVersion.indexOf('MSIE') > 0) ? 'inline' : 'table-cell';    // dodgy workaround because Microsoft doesn't understand the word "STANDARD"
	for (var i = 0; i < ths.length; i++) if (ths[i].className == 'optional') ths[i].style.display = (ths[i].style.display == '' || ths[i].style.display == 'none') ? display : 'none';
	for (var i = 0; i < tds.length; i++) if (tds[i].className == 'optional') tds[i].style.display = (tds[i].style.display == '' || tds[i].style.display == 'none') ? display : 'none';
}