Typically, the components of a complex VariableTypeare fixed and can be extended by subtyping. However, because each Variableof a VariableTypecan be extended with additional components this standard allows the extension of the standard VariableTypesdefined in this document with additional components. This allows the expression of additional information in the type definition that would be contained in each Variableanyway. However, it is not allowed to restrict the components of the standard VariableTypesdefined in this International Standard. An example of extending VariableTypeswould be putting the standard Property NodeVersion,defined in OPC 10000-3, into the BaseDataVariableType, stating that each DataVariableof the Serverwill provide a NodeVersion.