I have had opportunity to discuss in the office. The consensus is that to restore previously held STCW endorsements, all that would be required is whatever would be required to renew those endorsements at the time the national endorsement is taken out of continuity, plus any intervening one-time, gap-closing requirements that took effect while the national endorsement was continuity (e.g. Leadership and Managerial Skills, or ERM). It would not be necessary to repeat courses or assessments done previously.