Unique references are those which are specific to each attendee profile. They are predominately used for profile management between external registration systems and the Core, and attendee logins. Attendees can have one internal reference and one external reference.
Internal references are a unique string of numbers that are generated by the Core for each attendee. These are automatically determined when a profile is created and cannot be changed as they are used to identify profiles in the Core.
External references are a unique string of characters (not limited to numbers) that are populated by an event organiser when profiles are imported. These are used to identify profiles in the Core and may include Staff ID, registration number, ticket number etc. If not populated, this will remain blank.