The yellow code of epidemic situation means that there is no abnormality in epidemic prevention data verified by the national government service platform, but the health status of abnormal temperature measurement at the scene exceeds 37.3 degrees. Health codes are based on actual data and can be generated by citizens or people who have returned to work through online declaration and background audit. As an individual entering and leaving electronic certificate locally, the QR code can be declared once, which is universal in the whole city.