function checkFilter(t) {
	var a = document.getElementsByTagName("TR")
	for (i = 0; i < a.length; i++) {
		a[i].res = '';
	}
	a = document.getElementsByTagName("TD")
	for (i = 0; i < a.length; i++) {
		if (a[i].zoek == '1') {
			var v = false;
			if (a[i].innerHTML.toLowerCase().indexOf(t.value.toLowerCase()) > -1)
				v = true;
			a[i].parentNode.res = (v ? '1' : (a[i].parentNode.res == '1' ? '1' : '0'));
			if (v) a[i].res = t.value;
		}
	}
	a = document.getElementsByTagName("TR")
	for (i = 0; i < a.length; i++) {
		if (a[i].res != '') {
			if (a[i].res == '1') {
				a[i].style.display = 'block';
			} else if (a[i].res == '0') {
				a[i].style.display = 'none';
			}
		}
	}
}