This document provides mechanisms for a bidirectional mapping of built-in data types between OPC UA and XML. Some data types can directly be mapped in a lossless manner, for others the limitations are described.

The document defines specific OPC UA DataTypes for built-in XML data types that cannot directly be mapped and refers to an XML Schema for OPC UA DataTypes that cannot directly be mapped.

The scope of this document is not to provide a complete mapping of XML to OPC UA and vice versa. It only provides the base infrastructure by providing a mapping of built-in data types. How to map a full XML Schema with its attributes and elements to an OPC UA Information Model with ObjectTypes, VariableTypes, structured DataTypes, etc. depends on the concrete use case of the mapping and is not addressed in this document. This document can be used as a base for such a mapping.