GTIN is the new (since about 2005) naming structure for retail product identifiers, incorporating numbers/barcodes including EAN-8, UPC-12 and ISBN (from 2007).  Zoho has adopted distinct fields for these 4 trade identification numbers, which could all now be replaced by a singular GTIN field, bringing the terminology into alignment with retail standards.  This will facilitate easier scanning as the item is represented by a singular GTIN field rather than seperate fields depending on the market (USA vs rest of world) or product type (book etc.).  EAN, UPC and ISBN are now outdated terminology.