function aufzu(link) {
	if (document.getElementById((link + "z")).innerHTML != "-") {
		document.getElementById((link + "z")).innerHTML = "-";
		document.getElementById((link + "i")).style.visibility = "visible";
		document.getElementById((link + "bar")).style.visibility = "hidden";
	}
	else {
		document.getElementById((link + "z")).innerHTML = "+";
		document.getElementById((link + "i")).style.visibility = "hidden";
		document.getElementById((link + "bar")).style.visibility = "visible";
	}
}