When exchanging EDIFACT documents, the CONTRL message is used to syntactically acknowledge or reject, with error indication, an interchange, group or message received from a trading partner.
Note that CONTRL is the only message for acknowledgment in EDIFACT. In contrast, in
ANSI X12 there are two messages used for acknowledgment:
TA1 and
997/999 ACK.
Use of a CONTRL message for acknowledging receipt of an interchange, group or message is not required in EDIFACT. The use of
CONTRL is by trading partner agreement.