The GTIN (Global Trade Item Number) is a globally unique 14-digit number used to identify trade items, products, or services. GTIN is also an umbrella term that refers to the entire family of UCC.EAN data structures. This an optional field for listing an item - it is not required.
The family of data structures comprising GTIN include:
- GTIN-12 (UPC-A): this is a 12-digit number used primarily in North America
- GTIN-8 (EAN/UCC-8): this is an 8-digit number used predominately outside of North America
- GTIN-13 (EAN/UCC-13): this is a 13-digit number used predominately outside of North America
- GTIN-14 (EAN/UCC-14 or ITF-14): this is a 14-digit number used to identify trade items at various packaging levels
The GTIN field accepts values of 8, 12, 13, and 14 digits. There is a UPC check for values of 12 digits and the populating the GTIN field with a valid UPC will also populate the UPC field.
More information can be found at Global Trade Item Number.