The Transaction Link Identifier (TLID) is a new unique transaction identifier generated by Mastercard to provide a more consistent method for linking related activity after the original authorization. The TLID is being introduced in a phased, multi-year process for a smooth transition. In the future, Mastercard is expected to sunset current transaction identifiers and replace them with the TLID.

The TLID is logged when received from Mastercard in the authorization response; it not returned to the POS at this time.