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9.5. Appendix E: 020 Tag (ISBNs)

Last Updated 03/17/2025

MARC 020 Field

The ISBN can play a significant role in determining which bibliographic records are matched, overlaid, and/or merged during cataloging. When importing records and when attaching items, catalogers should carefully review the ISBNs listed in a record and determine whether they should be included in the record and whether they should be in the $a or the $z.

Records that come from vendors, OCLC, or other libraries (through Z39.50) may come with many ISBNs included for editions that should be in separate records in NC Cardinal (e.g. e-book, large print, audiobook, etc.) These records must be evaluated to determine which ISBNs should remain on the finished record, in either the $a or $z, and which should be stripped out of the record.

Remove both the 13- and 10-digit ISBNs from the bib record in cases where it is clearly does not belong on the record. These are some examples:

• ISBNs for an e-book if the record is for a print copy
• ISBNs for a print copy if the record is for an e-book
• ISBNs for the large print version if the record is for regular print
• ISBNs for the regular print version if the record is for large print

Put the ISBNs into the $z if it is associated with the bibliographic record, but should be ignored for matching, merging, and deduplication. You can learn more about the use of the $z here. Here are some examples:

• ISBNs for components of a kit that may be cataloged separately elsewhere in the catalog (See Cataloging Kits)
• ISBN for a book packaged with an audiobook if the bibliographic record is identified as a non-musical sound recording
• ISBN for a Blu-ray/DVD combo pack if the components are being cataloged on separate bib records
• ISBN for an item in hand if there is an existing record for a non-matching resource with the same ISBN in NC Cardinal (as when a publisher reuses an ISBN) and the records should not be merged