What Are Medical Library Accession Numbers?

As the national medical library of the United States and the largest medical library in the world, the National Library of Medicine (NLM) in Bethesda, Maryland, must be able to shelve books and non-book materials upon receipt, without waiting for them to be cataloged and assigned classification numbers. In the mid-1990s the NLM devised accession numbers that, when properly formatted, served this purpose.

Use

In 1994, the NLM began to use accession numbers to shelve books in the General Collection; ten years later, in 2004, they began to assign accession numbers to non-book materials located in the General Collection.

Components

NLM accession numbers have three components: year, upper-case letter and three-digit number. There is a space between the year and the upper-case letter and a dash between the upper-case letter and the three-digit number. The year is the year of receipt, the upper-case letter is assigned alphabetically beginning with the letter A and the three-digit number is sequential beginning with the number 001. An example of an NLM accession number for a book is 2011-A-999; an example of an accession number for a library item other than a book (e.g., an electronic resource) is 2010-AV-111.

Location in the MARC Record

The NLM enters the accession number in the 060 field of the MARC (MAchine-Readable Catalog) record. Unlike the classification number, which is entered in subfields "a" and "b," the entire accession number is entered in subfield "a" of the 060 field. When the classification number is assigned to the MARC record, it is entered in a separate 060 field; the result is that a fully cataloged NLM record has two 060 fields.

Search in LocatorPlus

LocatorPlus is a module of Voyager, the integrated library system used by the NLM. You can search LocatorPlus by numerous fields, including accession number. To do so, select the "Simple Search" tab, enter the accession number (e.g., 2007 A-102), and select "Call Number" from the list of indexes on the right. In the Holdings View of the record, you can see the accession number next to the words Call Number. In the MARC View of the record, you can see the accession number in the 060 field.

References

• NLM Technical Bulletin (Sept.-Oct. 1994): Subject and Call Number Field Changes to NLM Bibliographic Records
• NLM Technical Bulletin (Nov.-Dec. 2004): Accession Number Shelving of Non-Print Materials
• U.S. National Library of Medicine: Fact Sheet, LocatorPlus
• MARC 21 Format for Bibliographic Data: 060 - National Library of Medicine Call Number (R)