Health code verification code is empty.

Verification code is a picture generated by random numbers or symbols, and some disturbing pixels are added to the picture (to prevent OCR). Users can identify the verification code information with naked eyes, enter the form and submit it to the website for verification. Only after the verification is successful can a function be used.

The check code is a pre-set check program in the system, which detects whether the input is correct by comparing the input ontology codes. If they are consistent, it means that the code is entered correctly and the system allows input; If they are inconsistent, it means that the code has been entered incorrectly, and the system refuses to enter it, requiring re-entry of the code. Comparatively speaking, the security of check code is higher.