The Global TradeItem Number is an identifier for trade items, developed by GS1. Such identifiers are used to look up product information in a database which may belong to a retailer, manufacturer, collector, researcher, or other entity. The uniqueness and universality of the identifier is useful in establishing which product in one database corresponds to which product in another database, especially across organizational boundaries.
Format and incorporated standards
The GTIN standard has incorporated the International Standard Book Number, International Standard Serial Number, International Standard Music Number, International Article Number and some Universal Product Codes, into a universal number space. GTINs may be 8, 12, 13 or 14 digits long, and each of these four numbering structures are constructed in a similar fashion, combining Company Prefix, Item Reference and a calculated Check Digit. GTIN-8s will be encoded in an EAN-8barcode. GTIN-12s may be shown in UPC-A, ITF-14, or GS1-128 barcodes. GTIN-13s may be encoded in EAN-13, ITF-14 or GS1-128 barcodes, and GTIN-14s may be encoded in ITF-14 or GS1-128 barcodes. The choice of barcode will depend on the application; for example, items to be sold at a retail establishment could be marked with EAN-8, EAN-13, UPC-A or UPC-E barcodes. The EAN-8 code is an eight-digit barcode used usually for very small articles, such as chewing gum, where fitting a larger code onto the item would be difficult. Note: the equivalent UPCsmall format barcode, UPC-E, encodes a GTIN-12 with a special Company Prefix that allows for "zero suppression" of four zeros in the GTIN-12. The GS1 encoding and decoding rules state that the entire GTIN-12 is used for encoding and that the entire GTIN-12 is to be delivered when scanned.
Format and encodings
Note that GTIN-12 and GTIN-13 numbers can be encoded as GTIN-13 or GTIN-14 by adding initial padding zeroes. For GTIN-14, this indicates a "packaging level" of a single item. The numbering structure is as follows:
T1 - Indicator digit, used for GTIN-14, "1" to "8" indicates a packaging level and "9" a variable measure item. Zero in this position is not considered an Indicator Digit, but rather a pad or fill zero. There is, however, no worldwide consensus on which number indicates which packaging level and no significance should be built into this number.
T2 through T13 GS1 Company Prefix & Item reference number. The GS1 Company Prefix is allocated to the member company and the Item Reference is allocated by the user company. Each of these elements varies in length depending on the length of the allocated GS1 Company Prefix. Each different type of trade item is allocated a different number and, for ease of administration, it is recommended that companies do this sequentially.
T14 is a check digit, which follows the standard modulo 10 calculation.
All books and serial publications sold internationally have GTIN codes. The book codes are either constructed by prefixing the old 10-digit ISBN with 978, and recalculating the trailing check digit, or from 1 January 2007 issued as thirteen digits starting with 978. Each type of trade item is given its own GTIN, with the understanding that there is a potential need to retrieve predefined information from such items; this product or service may be priced, ordered, or invoiced at any point in the supply chain. This includes individual items as well as all of their different packaging configurations.
