property Data: TObject;

Data is a TObject property that can be used as a storage slot for data used by the command handler, and can contain a reference to any TObject descendant. Data can be accessed by a command action handler or event handlers triggered through execution of the item in TIdCommandCommandHandlers. 

Please note that it is the responsibility of the application to cast Data to the class instance required, or an exception will be raised. 

Data is not initialized in the Create constructor, nor is it released in the Destroy destructor. The application must assume all responsibility for maintaining Data when assigned.