Contains a code that identifies a merchant terminal. A unique code must be assigned to each terminal/POS device (e.g., a register) in a merchant location.
This code will be returned on the host response. In certain instances, the Terminal ID may be assigned by the merchant; in other instances, First Data assigns it.
The Terminal ID does not conform to the standard definition of alphanumeric fields: it is right justified and zero-filled on the left.
On a 0400 reversal message, this field must match the original 0100/0200 request