code: public void writeHeader(OutputStreamCounter os) throws IOException {
  		if (appendmode) {
  			os.write(HEADER[0]);
  		}
  		else {
  			os.write(HEADER[1]);
  			os.write(getVersionAsByteArray(header_version));
  			os.write(HEADER[2]);
  			headerWasWritten = true;
  		}
  	}
docs: Writes the header to the OutputStreamCounter.
  @throws IOException