An identity, or ID for short, is a variable data element that uniquely represents an item within a set of related items. IDs must be unique within a defined scope of data (encoding file, print file). If an ID must never have a duplicate for any usage (global scope), then the ID is a globally unique identifier (GUID).
The GoToTags NFC Encoder uses an Identity column to provide an optional unique identifier for the tag to be encoded. This is often used for correlated NFC tag encoding projects.