Comparison of OPC UA complex data models

OPC UA offers two complex data models. They do not have "official" names, but the historically first one is based on the DataTypeDictionary type, and the second one is based on the DataTypeDefinition type. We will therefore usually refer to them as "DataTypeDictionary model" (or "data type dictionary model"), and "DataTypeDefinition model" (or "data type definition model").

The table below summarizes the main difference between the two models.

	DataTypeDictionary Model	DataTypeDefinition Model
OPC UA version	1.00 and later (deprecated in 1.04 and later, but still available)	1.04 and later
Described in	OPC UA Specification Part 5 (Information Model)	OPC UA Specification Part 3 (Address Space Model)
Compatible with OPC UA Client-Server	yes	yes
Compatible with OPC UA PubSub	no	yes
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