A8. Feature Registry Central catalogue of all features used by the system. Each entry records the feature name, source dataset and field, transformation applied, proxy variable assessment (correlation with each protected characteristic, justification for retention or removal), and SHAP-based feature importance. Maintained by the Technical SME as part of the feature engineering layer. Updated when features are added, modified, or retired. Responsible party: Technical SME maintains. Regulations addressed: Article 10(2)(f) (examination for possible biases); Article 10(5) (special category data); Annex IV(2)(d) (data description). Key outputs

• Per-feature proxy variable assessment
• Feature importance ranking