Object-Fact Types can record a data-retention period: how long the data may be kept before it must be removed (GDPR storage-limitation principle).

The period is entered in a friendly form - a number plus a unit (Days / Months / Years) - and stored as a standard ISO-8601 duration (e.g. 'P7Y' for seven years). An empty value means no retention period is defined.

This complements the data sensitivity classification tracked in issue 0002735; together they form the GDPR metadata on a fact type. Finer detail (legal basis, DPIA reference, etc.) can be added via custom attributes.