To identify a message or package in the subject interchange, and to indicate that message s or package s acknowledgement or rejection (action taken), and to identify any error related to the UNH, UNT, UNO, and UNP segments.It can also identify errors related to the USA, USC, USD, USH, USR, UST, or USU security segments when they appear at the message or package level.
A code indicating acknowledgement, or rejection (the action taken) of a subject interchange, or part of the subject interchange, or indication of interchange receipt.