The System Users are managed in the itris Management Utility (IMU) in the System area.
System Users are similar to a normal itris user accounts, but it is not possible to log into itris itself with one of these users. They are primarily used when a service application such as the itris Agent or an API create or modify data in itris, in these scenarios that activity will be attributed to the System User.
To learn more about API’s see the article Integrations | API.