CSA Preface Standards development within the Information Technology sector is harmonized with international standards development. Through the CSA Technical Committee on Information Technology (TCIT), Canadians serve as the SCC Mirror Committee (SMC) on ISO/IEC Joint Technical Committee 1 on Information Technology (ISO/IEC JTC1) for the Standards Council of Canada (SCC), the ISO member body for Canada and sponsor of the Canadian National Committee of the IEC. For brevity, this Standard will be referred to as \"CSA ISO/IEC 8825-5\" throughout. This Standard supersedes CAN/CSA-ISO/IEC 8825-5:16 (adopted ISO/IEC 8825-5:2015). The International Standard was reviewed by the CSA TCIT under the jurisdiction of the CSA Strategic Steering Committee on Information and Communications Technology and deemed acceptable for use in Canada. This Standard has been formally approved, without modification, by the Technical Committee and has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. Scope This Recommendation | International Standard specifies two versions of a mapping from any XSD Schema into an Abstract Syntax Notation One (ASN.1) schema. The ASN.1 schema for both versions support the same semantics and validate the same set of XML documents. This Recommendation | International Standard specifies the final XER encoding instructions that are to be applied as part of the defined mapping to ASN.1 types, but does not specify which syntactic form is to be used for the specification of those final XER encoding instructions, or the order or manner of their assignment. NOTE – Implementers of tools generating these mappings may choose any syntactic form or order of assignment that results in the specified final XER encoding instructions being applied. Examples in this Recommendation | International Standard generally use the type prefix form, but use of an XER Encoding Control Section may be preferred for the mapping of a complete XSD Schema, as a matter of style. There are different ways (syntactically) of assigning XER encoding instructions for use in EXTENDED-XER encodings (e.g., use of ASN.1 type prefix encoding instructions or use of an XER encoding control section). The choice of these syntactic forms is a matter of style and lies outside the scope of this Recommendation | International Standard.