private function fig_cdata(Context $context) {
        $filename = $this->dataFile;
        $realfilename = dirname($context->getFilename()).'/'.$filename;
        if(! file_exists($realfilename)) {
            $message = "File not found: $filename called from: " . $context->getFilename(). '(' . $this->xmlLineNumber . ')';
            throw new FileNotFoundException($message, $filename);
        }
        $cdata = file_get_contents($realfilename);
        return $cdata;
    }