The UPN or unique pupil number is a 13-character code that identifies each pupil in the local-authority-maintained school system.


They are used in Impero Backdrop to track pupils records as they move through the school setting or to other schools using Backdrop.


If your school doesn't use UPNs as it is not part of a local-authority-maintained school system you can still use Backdrop to log and report on safeguarding concerns. 



If your school does not use UPN's, there is guidance here.