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ISO-9735

Application-level syntax rules for EDIFACT. The ISO standard that describes precisely how an EDIFACT message is written, byte by byte.

Definition

ISO 9735 is an international standard published by ISO/TC 154 (Processes, data elements and documents in commerce, industry and administration). It formalises the application-level syntax rules of the EDIFACT standard — distinct from the business semantics, which is governed by UN/CEFACT directives (D.YYA/D.YYB). The standard is published in several parts:

  • ISO 9735-1: syntax rules common to all parts (default separators ', +, :, ?, UNA structure, character repertoires).
  • ISO 9735-2: syntax rules specific to batch EDI (UNB/UNZ envelope).
  • ISO 9735-3: rules for interactive EDI (UIB/UIZ envelope).
  • ISO 9735-4: syntactic reporting (CONTRL and CONDRA).
  • ISO 9735-5: security rules (authentication, integrity, non-repudiation by USC/USA/USB signatures).
  • ISO 9735-6 to -10: key management, secure enveloping, object methods, etc.

Default service characters are precisely: ' (Segment terminator), + (Data element separator), : (Component data element separator), ? (Release character), . (Decimal mark), (Repetition separator in version 4 of the standard).

Origin

The first version of ISO 9735 was published in 1988, a few months after UN/CEFACT released the EDIFACT version 1 syllabus (1987). The objective of ISO: lock down normatively the rules that UN/CEFACT could modify independently from industry. Successive versions: 1988 (V1), 1990 (V2), 1992 (V3), 1998 (V4 with security), 2002 (V4 release 1 — split into 10 parts), with partial updates in 2009, 2014, 2015.

Example in context

A minimal EDIFACT envelope complying with ISO 9735-2:

Reading: UNA explicitly declares separators, UNB opens the interchange (sender 14 = DUNS, receiver 14 = DUNS), UNH opens an ORDERS D.96A message, UNT closes with 10 segments, UNZ closes the interchange with 1 message. All of this is governed by ISO 9735.

  • EDIFACT — the semantics attached to ISO 9735.
  • UNB — the interchange header normalised by 9735-2.
  • CONTRL — the syntactic acknowledgment normalised by 9735-4.
  • UNTDID — the UN/CEFACT repository.

Last updated: May 14, 2026