According to Randy, the following paragraph needs to be fixed or removed:

An example of a DataTypeDictionary is an XML document containing an XML schema. In this case, the DataTypeSystem is the W3C XML Schema and the top level element declarations in the schema document are the data type descriptions. Each of these descriptions is defined in different versions of an XML schema using the same XML target namespace. This target namespace is used as the namespace component of the DataTypeId in the Server’s AddressSpace. Since the same target namespace can be used in other XML schemas, Clients shall be aware that two DataTypeIds with the same namespace are not necessarily defined in the same DataTypeDictionary.