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- should ID be validated?
- should ID be assigned?
- is the ID required at sign up (that is, don't create an account until you've validated the external ID you're going to use for it)
- can the ID be unassigned or re-assigned? (you'd think no, but see below)
- can the ID be deleted once assigned? (you'd think no, but see below)
I would have this flag validate and assign an ID, require it at sign up, and not allow it to be unassigned, only deleted when the user is deleted (for testing).
ExternalId Table
- String studyId (key)
- String externalId (range)
- String healthCode
- long reservation
...