ISBN - International Standard Book Number.
An ISBN is a 10-digit number which is made up of:
Group identifier (1 digit, typically 0 or 1 for English-speaking countries),
Publisher identifier,
Title identifier,
Check digit.
ISBN for the Perl Cookbook: 1-56592-243-3
EAN - European Article Number.
EAN for the Perl Cookbook: 978-15659-2243-3.
MARC - MAchine Readable Cataloguing.
MARC records are widely accepted as the standard format for the interchange of bibliographic data.
Z39.50 - Information Retrieval Application Service Definition and Protocol Specification.
Z39.50 is a protocol for server-client text-searching and retrieval, deployed in application domains as diverse as libraries, geographic information and cultural heritage. Originally an American (ANSI/NISO) standard, it is now ratified as international standard ISO 23950.
ASIN - Amazon Standard Identification Number.