function limitCheckboxes(checkboxField, limit) {
		var formObj = checkboxField.form;
		numChecked = 0;
		limitAlert = false;
		for (var i = 0; i < formObj.elements.length; ++i) {
				if (formObj.elements[i].type == "checkbox") {
					 if (formObj.elements[i].checked == true) {
					 		++numChecked;
					 		if (numChecked > limit) {
								 limitAlert = true;
								 formObj.elements[i].checked = false;
							}
					 }
				}
		}
		if (limitAlert == true) {
			 alertText = "Sorry, you may not select ";
			 if (limit == 0) {
			    alertText += "any items";
			 } else {
			    alertText += "more than " + limit + " item";
					if (limit > 1) {
					   alertText += "s";
					}
			 }
			 alertText += ".";
			 alert(alertText);
		}
}