Commands for modifying the model.

The editor does not modify the model directly, but uses Command instances instead. Commands can be executed, redone and undone. The framework places the sequence of executed Commands on a CommandStack, which enables the undoing or redoing of command sequences.

Side note: Be careful when creating new instances of model elements in the redo or undo methods of a Command. Depending on how your commands are implemented, this can cause trouble when redoing or undoing a sequence of multiple commands.

More background information on the Command Design Pattern can be found in "Design Patterns", ISBN 0-201-63361-2.