public static function group($cn, $allowDashes = false)
	{
		$pattern = '/^[0-9a-z]+[' . ($allowDashes ? '-' : '') . '_0-9a-z]*$/';

		if (!preg_match($pattern, $cn))
		{
			return false;
		}

		if (self::nonNegativeInteger($cn))
		{
			return false;
		}

		// Is it a reserved group name?
		if (self::reserved('group', $cn))
		{
			return false;
		}

		return true;
	}