protected function checkIndicators($tagNo, $field, $rules)
    {
        for ($i = 1; $i <= 2; $i++) {
            $ind = $field->getIndicator($i);
            if ($ind === false || $ind == ' ') {
                $ind = 'b';
            }
            if (!strstr($rules['ind' . $i]['values'], $ind)) {
                // Make indicator blank value human-readable for message:
                if ($ind == 'b') {
                    $ind = 'blank';
                }
                $this->warn(
                    "$tagNo: Indicator $i must be "
                    . $rules['ind' . $i]['hr_values']
                    . " but it's \"$ind\""
                );
            }
        }
    }