When an item bears two or more standard numbers, a brief qualification may be added between parentheses, preceded by a space. Use the standard abbreviations pbk. (paperback), ed. (edition), v., vol., vols. (volume, volumes), pt., pts. (part, parts). Otherwise, record qualifying text as it appears on publications.

Do not record a price in tag 020 subfield $c (prior to November 2008, the price of UN sales publications was optionally recorded in 020 $c).

Examples:

020 $a 9280720877
020 $a 9280720872 (pbk.)
[Publication bears 2 ISBNs, one of which is for the paperback ed.]

020 $a 0765680092 (set : alk. paper)

020 $a 9027221677 (Eur)
020 $a 1556195214 (US)

020 $a 7010002282 (v. 1)
020 $a 7010012547 (v. 2)

020 $z 0835200028
020 $a 0835200019 (pbk.)
[Two ISBNs associated with one catalogue record, one of which is invalid (subfield $z)]

020 $a 9211317134 (print ed.)
020 $a 9211315220 (electronic ed.)

[Qualifiers appear on publication as "print edition" and "electronic edition"]

020 $a 9789292301095 (printed)
020 $a 9789292301101 (internet)

[Qualifiers appear on publication as "printed" and "internet"]

020 $a 9781844076963 (Earthscan pbk.)
020 $a 9781844076956 (Earthscan hardback)

[Qualifiers appear on publication as "Earthscan paperback" and "Earthscan hardback"]