用于检查数据的正确性。具体而言，在发送端，通过增加校验位，使有效数据位和校验位组成数据校验码；在接收端，根据接收的数据校验码判断数据的正确性。(For correcting the correctness of the data. Specifically, at the transmitting end, the valid data bits and the parity bits are added to the data check code by adding the parity b