The least significant bit of the cmd byte is the phase indicator, which is used to differentiate a new command from the retransmission of an old one.
命令字节的最小位是相位指示器，是用来区分一个新的命令还是老命令的重传。
2
The inside equipment seems a bit not well maintained. The ventilation fan switch is broken, and the interior floor indicator shows 'G' with the car actually at 1/F.
An indicator, usually a single binary bit, whose state is used to inform a later section of a program that a condition, identified with flag, had occurred.