It is to be recognized that numerous test methods are specific to particular optical fibre submarine cable system designs and are, therefore, proprietary information of the system designer/supplier. However, a common understanding needs to be met between the system designer/supplier and the system purchaser/operator on the general purpose of testing and the meaning of the results. Recommendation ITU-T G.976 highlights the purpose of testing in optical fibre submarine cable systems and lists the main test methods applicable to these systems. Specific test methods are described. This edition of the Recommendation includes the addition of test regarding electrical direct current resistance and the adoption of additional electrical integrity tests that may be conducted on cable samples after mechanical tests. Also reference to the latest transmission systems and relevant terms are included.