This Built-in DataType is used to define XML elements. OPC 10000-6 defines details about this DataType.

XML data can always be modelled as a subtype of the Structure DataType with a single DataTypeEncoding that represents the XML complexType that defines the XML element (it is not necessary to have access to the XML Schema to define a DataTypeEncoding). For this reason a Server should never define Variables that use the XmlElement DataType unless the Server has no information about the XML elements that might be in the Variable Value.