CONTRL
CONTRL is the UN/EDIFACT service (control) message used for technical acknowledgement: it confirms that a received interchange arrived and passed syntax checking, or it reports the syntax errors that caused it to be rejected. It answers the question "did my message arrive and parse correctly?" — at the envelope and syntax level, before any business processing happens.
CONTRL is the first half of the EDI acknowledgement pair. A positive CONTRL means the interchange is syntactically sound; the receiving application then processes the content and may return an APERAK for the application-level result. Without CONTRL, a sender has no reliable signal that a transmission was even received intact.
CONTRL is the delivery receipt of EDI. It tells the sender the interchange arrived and parsed — or exactly where the syntax broke — so problems are caught at the transport layer instead of surfacing hours later as silently missing bookings or status updates.
sent
errors reported
result
What does a CONTRL message confirm?
That a received EDIFACT interchange arrived and is syntactically valid — or, if not, which syntax errors caused it to be rejected.
How is CONTRL different from APERAK?
CONTRL is the technical/syntax acknowledgement (did it arrive and parse); APERAK is the application-level acknowledgement (did the application accept or reject the content).