Global Trade Item Number (GTIN) can be used by a company to uniquely identify all of its trade items. GS1 defines trade items as products or services that are priced, ordered or invoiced at any point in the supply chain.
Trade Item is identified with a GTIN by using 4 data structures: GTIN-8, GTIN-12, GTIN-13 and GTIN-14. If inserted into data bases, they are all recorded in a 14-digit data field. Choosing a data structure depends on the type of item and the field of user application.
The structure of GTIN includes:
The indicator can be used only GTIN-14 numbers. It has the value from 1 to 8 for fixed measure trade items and 9 for variable measure trade items.
The GS1 Company Prefix is part of the data structures used by GS1, except the GTIN-8 data structure. The GS1 Company Prefix provides access to all the applications, who use the identification standards of the GS1 System (for example to identify trade units and services, logistic units, assets and others).
Each company, that wishes to identify its products, shall receive a GS1 Company Prefix after its membership registration in the Member Organisation or at GS1. The Company Prefix varies in length and is usually determined by the number of items, which the company wishes to identify (100, 1000, 10 000 or 100 000).
The first two or three numbers N1, N2, N3 form the GS1 Prefix, administered by GS1. This does not mean that the product is manufactured or being supplied in the country carrying the GS1 Prefix. The number following the GS1 Prefix, is the company number allocated by the GS1 Member Organisation.
The GS1 Prefix and the Company number form the GS1 Company Prefix, which is allocated to each user of the GS1 System by the GS1 Member Organisation. For Bulgaria, the number is composed of either 7, 8, 9 or 10 digits, depending on the company’s needs.
Trade Item Reference Number is usually composed of 2 to 5 digits, non-significant, meaning that digits in the number themselves are not connected to a classification or contain any specific data. The most popular method for creating a data base of numbers is the sequential one, namely 0000, 0001, 0002, 0003, etc.
The Check Digit is the last digit (on the right) of the Global Trade Item Number (GTIN). It is calculated using an algorithm of its preceding digits in the number and is used to guarantee, that the barcode is validly scanned and that the number is composed correctly.