public function getIndexFromDBFData($field, $value)
    {
        foreach ($this->records as $index => $record) {
            if (isset($record->DBFData[$field]) &&
                (trim(strtoupper($record->DBFData[$field])) == strtoupper($value))
            ) {
                return $index;
            }
        }

        return -1;
    }