6.4. The safety case and the supporting safety assessment and the environmental impact assessment provide an iterative framework for the progressive improvement in understanding of the technical aspects of the disposal system, and for the identification of new monitoring data that should be collected. As the safety case and safety assessment progress through successive iterations, and as key issues are identified or resolved, the monitoring system should be adapted to accommodate the needs of the safety assessment. Conversely, as new information is identified from monitoring data, scenarios, conceptual models, or parameters used as part of the demonstration of safety may need to be updated. The progressive adaptation of the safety assessment and the associated monitoring, which are both directed at reducing uncertainty, is a key feature of the methodological approach to safety assessment.