*Correct Coding of ISBN in MARC21 field 020 in RDA &AACR2 Cataloging with Examples <http://resourcedescriptionandaccess.blogspot.com/2014/12/correct-coding-of-isbn-in-marc21-field.html>* Several years ago the definition of $z of the 020 (International Standard Book Identifier) was expanded—it is now used for “structurally invalid” ISBNs (those that are too short, too long, wrong check digit, etc.) and also for “application invalid” ISBNs (ISBNs for a manifestation that would be described in a different bibliographic record)... Read complete post on RDA Blog>> <http://resourcedescriptionandaccess.blogspot.com/2014/12/correct-coding-of-isbn-in-marc21-field.html> Salman Haider -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.