private void extractDocumentIdentifier(InputStream inputStream, Metadata metadata)
            throws IOException {
        byte[] bytes = new byte[36];
        int read = IOUtils.read(inputStream, bytes);
        if (read == 36) {
            metadata.set(IWORKS_DOC_ID, new String(bytes, StandardCharsets.ISO_8859_1));
        }
    }
All iWork 13 files contain this, so we can detect based on it
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-apple-module/src/main/java/org/apache/tika/parser/iwork/iwana/IWork13PackageParser.java