Interchange Control Reference
The number that seals an EDIFACT interchange — identical in the opening UNB and the closing UNZ.
Definition
Element 0020 is generated by the sender and should be unique and ideally sequential per partner. It appears in the UNB (header) and then, identically, in the UNZ (trailer): the receiver compares the two to confirm the interchange was not truncated. Its sequence also helps detect missing or duplicate interchanges and feeds the CONTRL technical acknowledgement.
Origin
Defined as data element 0020 in ISO 9735 (UN/EDIFACT Syntax Rules), maintained by ISO/TC 154 and published in UN/CEFACT's UNTDID directory.
Example in context
UNB+UNOA:3+SENDER+RECEIVER+260620:1430+5001' then UNZ+1+5001' — reference 5001 must match.