The current level of OTC ISIN record generated by the DSB is designed to enable users to fulfil their RTS-23 reporting obligations and is aligned with ESMA’s needs at a minimum.

An extract of the relevant requirements are set out below “Given the scope of the financial instruments to be covered (about 15 million), the use of multiple identifiers for the purposes of data reporting under MiFID II/MiFIR would lead to difficulties in obtaining a comprehensive overview of markets and render market surveillance extremely difficult as different identifiers have to be
reconciled. It would also considerably increase the workload for ESMA and National Competent Authorities to analyse the data, and would lead to considerable costs due to the costs of underlying reference data.” with full details available here: https://ec.europa.eu/finance/securities/docs/isd/mifid/rts/160714-rts-23_en.pdf.