SE
Transaction Set Trailer. The closing segment of a Transaction Set — completeness check and echo of the number declared in ST.
Definition
In the ANSI ASC X12 standard, SE is the mandatory closing segment of any Transaction Set (850, 810, 856, 997, etc.). It performs two structural checks:
- SE01 — Number of Included Segments (element 96): total number of segments in the Transaction Set, ST and SE included. The receiver counts segments and compares. Any mismatch triggers a syntactic rejection (AK9 segment count mismatch in 997).
- SE02 — Transaction Set Control Number (element 329): control number, identical to ST02. Detects truncated or out-of-sync transactions.
Origin
The ST/SE pair has been defined in X12 since version 002001 (1985). Like ISA/IEA and GS/GE, SE is purely syntactic: no business data, only structural invariants. Maintained by ASC X12.
Example in context
Reading: 7 segments total (ST, BEG, REF, N1, PO1, CTT, SE), control
number 0001 identical to ST02. If the receiver counts 6 or
8, the Transaction Set is rejected.