The userId field on a UserEmail record in Skarn Suite (the platform auth hub: SSO, tenancy, billing, entitlements, internal event bus) stores a specific piece of the data; it is a reference linking this UserEmail record to the related record it belongs to, so the application can join them and present connected data together. In everyday use this is part of how UserEmail records are created, displayed, validated, and reported, and it is grounded strictly in the real schema fact UserEmail.userId: String.
Technical section
Data model, API, and internals — visible to developers.