In case a 'big bang' migration is not possible, divide the migration into Implementation Stages. Define a 'big bang' migration when no intermediate stages are possible or needed. Compose implementation stages based on architectural significance; architectural coherence and migration strategy (e.g. benefit logic). This task is mainly an update of the already available Migration Design, before the detailed design of the next Implementation Stage is started. If the Migration Design does not need updates this task can be skipped.