Get a MARC Organization Code

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MARC Organization Codes represent names of libraries and other organisations so they can be identified in the bibliographic environment. If your library doesn't have a code, you can ask us for one.

Apply for your MARC code

  1. Check your organisation does not already have a MARC code by searching the Directory of MARC codes for UK organisations (PDF format 1,257 KB) or (CSV (ZIP 151 KB)
  2. If your organisation does not have a MARC Organization Code, please complete the request form (MS Word 26 KB) and send it to Please submit this form as a Word document, not a PDF.
  3. We will assign a MARC code if you are eligible.

Directory data is distributed under a Creative Commons CC0 1.0 Universal Public Domain Dedication licence. See our terms and conditions.

If you're unsure about whether your institution or a particular sub-unit of your institution already has a MARC code or you would like further information, please e-mail

We process requests for a MARC code for one organisation within a few days.

If you require codes for more than one organisation, or for multiple sub-units of one organisation, processing will take longer. The process time will be assessed on a case-by-case basis. Please contact us to discuss.

The British Library is responsible for the assignment of MARC codes for organisations in the UK, together with Crown Dependencies and Overseas Territories. We also assign ISILs to institutions in the UK and its dependencies (ISILs are based on MARC codes).

The Library of Congress is responsible for assigning MARC Organization Codes to institutions in the Republic of Ireland.

What are MARC Organization Codes?

MARC Organization Codes (formerly known as NUC codes) represent names of libraries, other kinds of organisations or sub-units of organisations that need to be identified in the bibliographic environment.

MARC Organization Codes are 8-character variable length codes; this may include a dash. The codes include uppercase and lowercase characters in order to be more human-readable and are case-insensitive.

The codes are used in whatever context requires an institutional identifier, for example in MARC bibliographic records to identify the organisation creating or modifying a record; in systems reporting library holdings and in various types of cooperative projects.

Although the Library of Congress has taken the lead in the assignment of MARC codes, generally speaking MARC codes are nationally based. The ISIL takes advantage of these nationally based codes to create an international identifier.

Further information

The British Library
Metadata Standards
Boston Spa, Wetherby
West Yorkshire
LS23 7BQ
United Kingdom

Tel: + 44 (0) 1937 546124
Fax: + 44 (0) 1937 546586