Context

A production system contains historical business information from which a domain state or classification is derived. The business later introduces a revised interpretation of that concept while the underlying historical facts remain unchanged.

Trigger

The revised interpretation must be applied retrospectively so that previous and revised results can be compared for historical cases.

Acceptance Criteria

• The revised interpretation can be evaluated for 100% of a representative sample of at least 100 historical cases using information captured before the revised interpretation existed
• 0 historical source facts are modified, deleted, or rewritten to produce the revised interpretation
• 0 existing producers of those historical facts require modification solely to support the retrospective interpretation
• The previous and revised interpretations can be evaluated side by side for the same sampled historical cases
• 100% of revised results in the sample can be traced to the source facts used to derive them
• Where an explicit business policy determines the interpretation, 100% of sampled results identify the policy version used
• Introducing the revised interpretation changes no more than 3 existing modules or independently deployable components, excluding tests, documentation, and the new interpretation itself
• Existing consumers that continue to use the previous interpretation require 0 modifications

Measurement & Verification

Select a domain concept whose business meaning changed after production history already existed. Run the previous and revised interpretations against a representative sample of at least 100 historical cases and verify the criteria through automated tests, version-control diff, migration history, and data lineage.