Overview
ISO 9735-8:2002 is Part 8 of the EDIFACT application-level syntax rules and specifies how to include associated data in EDI interchanges. Associated data are data objects that cannot be represented within standard EDIFACT messages (for example, product model data from STEP or drawings from CAD). This part defines package and object structures, referencing mechanisms, and conformance constraints so that non-message payloads can be exchanged reliably alongside EDIFACT messages.
Key practical points:
- A package contains an object header (UNO), an object (a stream of octets), and an object trailer (UNP).
- Objects are not constrained by the interchange character repertoire and are not subject to EDIFACT syntax escaping rules.
- Objects can be referenced from messages by object identification numbers (e.g., via RFF segments).
- Interchanges may contain messages, packages, groups, or combinations of these structures.
Key Topics
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Package structure: The standard mandates UNO / object / UNP as the atomic package. This structure enables embedding arbitrary binary or text objects inside an EDIFACT interchange while preserving clear boundaries.
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Object content and character repertoire: The object is treated as a stream of octets; its internal character set or encoding is outside the scope of the interchange header. Service characters inside an object are not interpreted as EDIFACT syntax.
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Object referencing: Objects are identified by an object identification number in the UNO segment (S020). For UN/EDIFACT messages, an RFF segment is used to reference the applicable object ID. Object IDs should be unique for a sufficient time to avoid ambiguity.
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Interchange and grouping rules: An interchange may contain only messages, only packages, both, or groups containing either. The specified header/trailer order (e.g., UNB/UNZ, UNG/UNE) must be preserved for batch and interactive interchanges.
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Conformance: ISO 9735-8 uses Syntax version number "4" (data element 0002 in UNB) and release "01" (data element 0076 when used). Conformance to this part requires conformance to ISO 9735-1 and ISO 9735-10 and either ISO 9735-2 or ISO 9735-3 as applicable.
Applications
- Exchange of large or binary engineering artifacts (STEP, CAD) alongside commercial EDI messages.
- Packaging of auxiliary documents (specifications, drawings, certificates) that must be referenced by business messages.
- Use cases requiring interoperable object identification and retrieval within existing EDIFACT interchange workflows.
Related Standards
- ISO 9735-1: Common syntax rules across all parts (mandatory for conformance).
- ISO 9735-2 / ISO 9735-3: Batch or interactive syntax rules (one required depending on use).
- ISO 9735-10: Syntax service directories and segment specifications used for UNO/UNP and message headers.
By following ISO 9735-8:2002, organizations can extend EDIFACT interchanges to carry complex associated data while preserving interoperability, clear object referencing and adherence to the UN/EDIFACT framework.