UK - Data migration of historic leavers

Summary:

What is the correct process for data migrating UK historic leavers into HCM payroll?

Content (please ensure you mask any confidential information):

There is a doc page which says these two fields must be set for any historic leavers (who have already been reported to HMRC as leavers in the legacy system) being data migrated into the system. It doesn't explain what exactly these fields do though. I suspect the first is just to populate the termination date field on the FPS, but what does the second field do?

• DATE_LEFT_REPORTED_HMRC: Indicates the date already reported by the legacy FPS process submission. The Oracle Cloud HCM payroll process uses this termination date in any future FPS submissions, as required.