ANSI-X12-5
ANSI X12.5 Interchange Control Structure. See official source.
Definition
X12.5 is the substandard that specifies the interchange envelope: ISA and IEA segments, their declared separators and the control rules (sequence numbers, group counts).
Origin
Published by ASC X12; refreshed version after version. X12.5 complements X12.6 (Application Control Structure for GS/GE) and X12.3 (data elements).
Use
The ISA segment, defined by X12.5, occupies the first 106 characters of every X12 interchange and declares the separators used in the rest of the stream. Strict adherence to X12.5 is what allows any market EDI translator to recognise the interchange.