There are three health codes: green, yellow and red. Each color has a different meaning. Users need a green code to facilitate travel. Some people have black codes for the following reasons:
1, the health code is black, indicating that the health code applied by the user is under review. When the review is completed, the green code, yellow code and red team will be displayed.
2. The image has not been refreshed. Click the refresh button to try.
3. The user failed to authenticate successfully or failed to authenticate. Please try authentication again.
4. There is no location service.