Upgraded from Version 1 to 3. PER_SENIORITY_DATES_F - How is it Populated?

Summary: New table PER_SENIORITY_DATES_F created as part of upgrade to version 3. Can any one share the details of the data migration to this table?

Content (required):

From what I can tell - and in the context of the ORIGINAL_DATE_OF_HIRE, data was migrated from PER_PERIODS_OF_SERVICE into PER_SENIORITY_DATES in version 1 or prior (perhaps this was done manually?)

Then, as part of the version 3 upgrade, ORIGINAL_DATE_OF_HIRE data was migrated from PER_SENIORITY_DATES to PER_SENIORITY_DATES_F (as well as from PER_PERIODS_OF_SERVICE to PER_SENIORITY_DATES_F, in the case of prior periods of service).