private int parseSpanConstraint(String str) {
		if (str == null) return 1;
		if (str.equals("relative")) return RELATIVE;
		if (str.equals("remainder")) return REMAINDER;
		try {
			return Integer.decode(str).intValue();
		} catch (NumberFormatException ex) {
			throw new ErrorException("TableConstraints: Illegal span constraint");
		}
	}