code: private byte[] packRules()
      {
          byte[] rules = new byte[6];
          rules[0] = (byte)startDay;
          rules[1] = (byte)startDayOfWeek;
          rules[2] = (byte)endDay;
          rules[3] = (byte)endDayOfWeek;
  
          // As of serial version 2, include time modes
          rules[4] = (byte)startTimeMode;
          rules[5] = (byte)endTimeMode;
  
          return rules;
      }
docs: Pack the start and end rules into an array of bytes.  Only pack
  data which is not preserved by makeRulesCompatible.