This document complements the ISO 20022 Metamodel, as specified in ISO 20022-1, with generic requirements and guidelines to define specific syntax generation rules for other encodings in order to produce schemas based on each specific syntax generation rules in compliance with this document. Such specific syntaxes include XML, ASN.1 and JSON. (XML and ASN.1 do not imply ISO 20022-4 XML schema generation and ISO 20022-8 ASN.1 generation only. W3C XML Schema, ASN.1 and JSON can be used to express or define a variety of schema types.)

Under this metamodel-driven and syntax-agnostic approach of ISO 20022 series, interoperability is ensured at the conceptual level of the metamodel specified in ISO 20022-1, rather than at the physical level of syntaxes specified in ISO 20022-4 and ISO 20022-8.

In this document, "schema" refers to the "SyntaxMessageScheme" defined in ISO 20022-1. However, for ease of reading, this document will hereafter refer to it as "schema" which is a general term for design documents that define data structures.

The metaclass “MessageDefinition” that is described in ISO 20022-1:2026, Figure 13 is the target of the transformation specified in this document, but the metaclass “MessageChoreography” is not. In other words, this document is only the rules for the syntax of the data representation language. For example, Application Programming Interface (API) specific aspects are outside the scope of this document.

Regarding the concept of conformance to this document, see Annex B.