code: private static void initAllocationTable(File atFile, int blockCount, int blockSize, boolean forceSync) throws DataStoreException
      {
          log.debug("Creating allocation table (size=" + blockCount + ") ...");
  
          // Create the file
          try
          {
              FileOutputStream outFile = new FileOutputStream(atFile);
              DataOutputStream out = new DataOutputStream(new BufferedOutputStream(outFile));
  
              out.writeInt(blockCount); // Block count
              out.writeInt(blockSize); // Block size
              out.writeInt(-1); // First block index
              for (int n = 0 ; n < blockCount ; n++)
                  out.write(EMPTY_BLOCK);
              out.flush();
              if (forceSync)
                  outFile.getFD().sync();
  
              out.close();
          }
          catch (IOException e)
          {
              throw new DataStoreException("Cannot initialize allocation table " + atFile.getAbsolutePath(),e);
          }
      }
docs: one 0 byte and three -1 ints