To qualify for a Maryland High School Diploma by examination, a candidate shall earn the minimum passing score for each test module and the overall passing score for the entire battery of the Test established by the testing service. Once a candidate receives a passing score on an individual module, that score remains valid towards the achievement of a Maryland High School Diploma until a new series of tests has been issued by the testing service. In the event that a new series of tests has been issued, the Secretary may determine how and for how long passing scores on the previous series can be applied to the achievement of a Maryland High School Diploma.