ISSNs and ISBNs

Overview of ISSNs and ISBNs.

ISSNs and ISBNs are supposedly-unique¹ identifiers for serials and books (respectively) which can be used to locate materials. ISSNs and ISBNs are composed of numbers and possibly the upper-case letter "X" in the final position (check-digit). They may be displayed with hyphens or without hyphens.

ISSNs

ISSNs should consist of 8 digits (or X), possibly with a hyphen in the middle, e.g. 0090-001X or 00448399. In catalog records, these should have the hyphen. However, people searching may or may not enter the hyphen. A record may contain multiple ISSNs, since one may be for the electronic version of the periodical and one for the print.

ISBNs

ISBNs come in two lengths, 10 and 13 digits (or X). These may be hyphenated in quite a few ways (depending on the country in which the item was published). In the catalog records, these should not have the hyphens. A record may contain many ISBNs, since there will be different ISBNs for different versions such as hardcover and paperback. These are often included in the same record.

These should be displayed in records but will also be needed in search, since they're generally a way of finding the exact thing you want.

Note 1. ISBNs, in particular, may get reused by publishers. This is generally a result of poor data management practices.

MARC Fields

MARC field	description	expected formatting	label	usage
020aqz	an identifier for a book or similar bibliographic resource. Subfield a is the primary identifier. z is a cancelled one. q is descriptive info about the item intended for display (e.g. specifying that an ISBN is for the hardback).	expected value of a or z is 10 or 13 digits or final X, formatted without hyphens	ISBN	Display
020az	these are the two possible actual values, without the qualifying/descriptive info for display	With and without hyphens		Index
022a	an identifier for a serial or periodical resource. subfield a is the primary identifier. We will only display 022a.	8 digits or final X, formatted as NNNN-NNNN	ISSN	Display
022a:022l:022m:022y:022z	Includes fields used for linking or are canceled or inaccurate ISSNs which people still may use to search for materials using outdated info	With and without hyphens		Index

Display

We'll display each separately.

• For ISBN display, we include all values with qualifying fields.
• For ISSN display, we only use the subfield a, the valid ISSN.

Search

Advanced Search includes a field for ISBN or ISSN search. This field should search either.

ISBNs and ISSNs should be included in keyword search.

ISSN and ISBN search should work both with and without hyphens. Since the data for ISSNs has hyphens and ISBNs it does not have hyphens, this may require some logic in indexing and stripping hyphens.