ISO 20022-8:2013

Overview

ISO 20022-8:2013 - "Financial services - Universal financial industry message scheme - Part 8: ASN.1 generation" defines deterministic transformation rules to generate ASN.1 abstract syntax from an ISO 20022 MessageDefinition. It formalizes a Level 3 → Level 4 conversion so that every ISO 20022 MessageDefinition maps predictably to an ASN.1 module used for message description and validation. The output is machine-consumable ASN.1 (.asn) files packaged per MessageSet (ZIP of PDUs), with metadata comments inserted by the generator.

Keywords: ISO 20022-8:2013, ASN.1 generation, ISO 20022, MessageDefinition, MessageSet, ASN.1, abstract syntax, encoding, XER, PER, ECN

Key technical topics and requirements

• Deterministic transformation: The conversion from MessageDefinition to ASN.1 is fully deterministic - no manual input or manual adjustment of results is permitted.
• Mapping rules: Each MessageDefinition is mapped to a single ASN.1 Module containing a single PDU; each Module is stored as a ".asn" file. Each MessageSet becomes a collection of PDUs in a ZIP package.
• Encodings:
  • Default encodings: Aligned Packed Encoding Rules (PER) and XML using XER are the standard defaults.
  • Custom encodings: Additional ASN.1 encodings may be registered; non‑standard encodings must be described in Encoding Control Notation (ECN) and registered in the Repository.
• Repository and Registration: ASN.1 appears in the ISO 20022 Repository as a SyntaxScheme. EncodingSchemes (per ISO/IEC 8825 encodings) must be added to the Repository; the Registration Authority manages registration.
• Scope of ASN.1 output: The generated ASN.1 provides the abstract syntax for structural description and validation but does not replace the MessageDefinition as the definitive semantic source.
• Metadata: Generated files include comments with generator metadata such as Registration Authority release number and generation date.

Practical applications and users

• Who uses it:
  • Financial institutions and payment processors implementing ISO 20022 messaging
  • Middleware, messaging gateway and protocol stack vendors
  • Integration engineers performing message validation, conformance testing, and interoperability work
  • Registration Authorities and standards implementers
• Practical benefits:
  • Alternative to XML Schema (XSD): Provides a compact, efficient schema language suited for constrained environments and high-performance parsing.
  • Multiple encoding options: Offers wire-format flexibility (PER, XER, custom encodings) to optimize bandwidth, speed, or legacy compatibility.
  • Interoperability: Deterministic mapping ensures consistent ASN.1 modules across implementers, simplifying conformance testing and library generation.
  • XML compatibility: When encoded with XER, ASN.1 messages produce XML equivalent to the ISO 20022 XSD representation.

Related standards

• ISO 20022 series: ISO 20022-1 (Metamodel), -2 (UML profile), -3 (Modelling), -4 (XML Schema generation), -5, -6, -7 (Registration)
• ASN.1 standards: ISO/IEC 8824 (ASN.1 abstract syntax), ISO/IEC 8825 (ASN.1 encodings), ISO/IEC 8825-5 (XSD ↔ ASN.1 mapping)
• XSD / XML: W3C XML Schema Part 2 (datatypes) and the ISO 20022 XSD generation rules (ISO 20022-4:2013)

This standard is essential for architects and implementers choosing ASN.1-based ISO 20022 deployments, ensuring consistent, registered ASN.1 artifacts and controlled encoding strategies.