The person record and effective dating

One person, one record, forever — a person who leaves and returns is the same record with a new work relationship, which is the principle that prevents duplicates. Then effective dating properly explained: update creates a change from a date forward and preserves history, correct amends an existing record and overwrites it. Update for real-world changes, correct for data entry errors. Using correct on a genuine change destroys history and is the most common irreversible user error in HCM.