User IDs (UIDs) associated to Validic Users

This article pertains to: Legacy API (V1)

What forms of data do you accept for a user ID (UID)?
Can we use a users email address as their UID, for instance?

Any unique identifier is allowed as long as it could not be used to identify the user. For instance, email addresses and social security numbers are not valid UIDs.

Identifying UIDs may not be used because they would break the HIPAA & GDPR de-identification for the Validic dataset.