There is no universal standard instrument identification scheme. Although the OpenFIGI (https://openfigi.com/) and the Open PermID (https://permid.org/) initiatives are beginning to address this, different organisations and counterparties use different identity schemes. For example, inbound data sources such as market quotes data are often keyed on different identity schemes from a custodian's overnight files.
To overcome these challenges LUSID has an internally unique ID for every Instrument, called the 'LUSID Unique Instrument Identifier' (aka ‘LUID’).
In addition to LUIDs, instruments in LUSID:
- must also be associated with at least 1 unique market identifier, e.g. OpenFIGI or an internal unique identifier generated by your Security Master
- can be associated with as many non-unique identifiers as you like, e.g. ISIN, SEDOL, Ticker
By allowing you to add multiple identifiers to an instrument you can then decide, on a case by case basis, which identifier should be used to resolve the instrument. For example, to resolve an instrument to market quotes data you may choose to use a ticker, whereas you may book trades using a Open PermID or OpenFIGI. Because all instruments are backed by the LUSID Unique Instrument Identifier you can be certain that although you have referenced this instrument through two different identifiers you are in fact referring to the same instrument.
For more details see how does LUSID resolve Instruments?