protected function getOkFilenames()
    {

        // initialize the array for the available okFilenames
        $okFilenames = array();

        // prepare the OK filenames based on the found CSV file information
        for ($i = 1; $i <= sizeof($patternKeys = $this->getPatternKeys()); $i++) {
            // intialize the array for the parts of the names (prefix, filename + counter)
            $parts = array();
            // load the parts from the matches
            for ($z = 0; $z < $i; $z++) {
                // append the part
                $parts[] = $this->getMatch($patternKeys[$z]);
            }

            // query whether or not, the OK file exists, if yes append it
            if (file_exists($okFilename = $this->prepareOkFilename($parts))) {
                $okFilenames[] = $okFilename;
            }
        }

        // prepare and return the pattern for the OK file
        return $okFilenames;
    }