Use of Event Registration IDs
I am using the API to determine if members have registered or their registration has been cancelled for an Event.
At the moment I cannot see any way of knowing that a registration has been cancelled from the API.
So, I will need to check if the registrations have changed or not since the last time it was checked. This means saving the Event Registration IDs in a file.
What is the valid range of a Registration ID?
Unfortunately there is no edit timestamp in event registration data structure.
Registration Id could be any integer from 0 to 2147483647.
In your case I would recommend to store all registrations as JSON in some file or database and check it’s state from time to time.