code: void writePayload(ByteArrayOutputStream os)
  	{
  		// RF frames don't use NPDU length field
  		os.write(addInfo[ADDINFO_RFMEDIUM] != null ? 0 : data.length - 1);
  		os.write(data, 0, data.length);
  	}
docs: /* (non-Javadoc)
  @see tuwien.auto.calimero.cemi.CEMILData#writePayload(java.io.ByteArrayOutputStream)