TID
Terminal IDIdentifiers
The unique identifier assigned by the acquirer to an individual payment terminal or virtual terminal under a MID. Multiple TIDs can sit under one MID, typical for chains with multiple POS locations or merchants with multiple checkout flows.
In practice.
The TID identifies a specific terminal or integration point under your MID. In card-present and multi-channel setups it is mostly plumbing, but it matters in reconciliation and in scheme reporting, where issues are often traceable to one terminal rather than the whole account.