National accounts of 1970-1975 founded on a new base - National annual accounts with 1971 as base-year have just been substituted to the former accounts base 1962 = 100. Even if the general concept of the new accounting frame is not very far from that of the former one, as was pointed out in a recent issue of Économie et Statistique (*), operations' definition and that of economic agents' categories, were rather largely modified. Seeing that, it proves difficult for users of accounts to appreciate the nature and amplitude of the evaluations' revision which matched the changes interfered in the system. The object of the present article consists in supplying items of answer to this question with regard to the period of time extending from 197...