MiFID II will require a far wider use of ISIN codes, which are to be applied in many cases to OTC derivatives and has been previously posted (see here). This article on the Financial Technologies Forum outlines the contents of this paper from ANNA, proposing a scheme for generating such codes. At the same time, this post on the Fidessa Regulation Matters blog thinks about which instruments will require the same ISIN, and which will be different, in the case of OTC trades.