Xuchang's low-risk home isolation is that the yellow code can automatically return to the green code after seven days. The yellow code indicates the need for home isolation, and the red code indicates the need for centralized isolation. One of the transcoding rules of health code is to code according to the roaming information of mobile phone signals, and the health code will be automatically converted into yellow code or red code according to the different risks of the areas where mobile phone signals have roamed. It can automatically return to green code after seven days.