Electronic Data Interchange (EDI) - a broad term for the online exchange of structured data relating to commerce. EDI standards, such as EDIFACT and EDItX, were developed to carry information regarding commercial transactions but not to carry product metadata with the fullness and form suitable for public display that can be carried in ONIX. EDIFACT or EDitX are used when the information supplied is for business-to-business transactions only and will not be displayed to the public as descriptive information about a book.
EDItEUR - the international group coordinating development of the Thema and ONIX standards for books, ebooks, and serials. They provide free ONIX documentation and support for ONIX implementation. They also maintain the EDIFACT and EDItX standards used for electronic communication of business-to-business transaction information.
GTIN (Global Trade Item Number/GTIN-13) - a universal product identifier system for products that are bought and sold in the marketplace. GTINs may be 8, 12, 13, or 14 digits long. The expansion of the ISBN to thirteen digits created conformance to the GTIN-13 standard, making ISBN consistent with other non-book products. All book and serial publications sold internationally are expected to carry GTIN-13.
Identifier - a language-independent label that uniquely "names" an object within an identification scheme. Language-independent means that the identifier is a numeric or alphanumeric code (rather than a book title or a personal name, for example) that always refers to the same thing. Identification schemes define the rules for constructing the identifier, including how many characters it contains and what those characters stand for. ISBN, ISSN, ISNI, and ISTC are examples of standard, publishing industry-approved identifiers. The use of the ISBN in publishing, for example, allows accurate communication about a particular book product without needing to state the title, publisher, binding, price, and other version-specific information in every transaction. It helps ensure that the correct version of a book is delivered to the customer and that sales information is accurately captured.
Individual vendors may assign proprietary identifiers (Amazon ASINs or vendor SKUs, for example) to their products, but these are useful only within the vendors' systems and are not internationally recognized or controlled. A proprietary product number should not take the place of an industry-approved standard identifier, although both numbers may certainly co-exist within a bookseller's system. Identifiers that are accepted and controlled globally, such as ISBN, ISSN, ISTC, and ISNI, are recognized and interpreted across multiple systems and bookseller e-commerce sites.