function disableOberflaeche(Deactivate) {
	if(Deactivate == true) {
		document.search_form.searchfor_oberflaeche.value = "";
		document.search_form.searchfor_oberflaeche.disabled = true;
	}
	else {
		document.search_form.searchfor_oberflaeche.disabled = false;
	}
}

function check_form(obj) {
	if(obj.selectedIndex == 2)	 {
		disableOberflaeche(true);
	}
	else {
		disableOberflaeche(false);
	}
}