ISIN
The international code that identifies a security unambiguously: every issue has its own.
How to read the number
One issuer may have dozens of issues with nearly identical names; telling them apart by name is impossible, by code straightforward.
When the metric lies
The exchange ticker of an issue and this code are different identifiers, and the ticker can change. A search by name returns neighbouring series of the same issuer on entirely different terms.
Also known as: international securities identification number