FISD is acting as a neutral facilitator of the discussion. The discussion with ANNA confirms that ISIN is a unique identifier per the ISO-6166 standard and the ISIN guidelines for fungibility. The Problem Financial instruments can be issued, priced, traded and settled in many ways.
Different identifiers are relevant at various levels.
There are a number of reasons why a multi-level product identification scheme might be desirable. Exchanges are developing multiple trading linkages allowing their members trading access to securities held on other exchanges. In essence, securities registered on one exchange may be traded on a linked exchange. Registers of securities are not exchange or country dependent and the same security can be registered in one or many locations and traded in each. In addition, inter-depository links allow settlement to occur in multiple locations.