The International Standard Identifier for Libraries and Related Organisations (ISIL), ISO 15511, assigns unique identifiers to libraries and related organisations, such as archives and museums.
[1] The Danish Agency for Culture and Palaces is the international authority for maintaining the standard and its registry.
[2] Valid symbols are A-Z, 0-9, solidus (/), hyphen-minus and colon.
An ISIL consists of a prefix identifying the authority which issued the ISIL, a dash, and then an identifier issued by that authority.
Global-level identifiers can also be assigned, which are not associated with a particular country, e.g. 'oclc-' for the OCLC.