gtin property
//www.gs1.org/standards/Digital-Link/) expresses GTINs as URLs (URIs,
IRIs, etc.). Digital Links should be populated into the
SchemahasGS1DigitalLink attribute.
Note also that this is a definition for how to include GTINs in Schema.org data, and not a definition of GTINs in general - see the GS1 documentation for authoritative details.
Implementation
String? gtin;