Provides events when some command operations modify the state of the Design Engine.

## Package Specification

The application modifies a report design using a set of commands. Each command will send notification event and throw exception if an error occurs.

- An exception thrown if an error occurs. Many exceptions provide detailed error codes to clearly identify what went wrong.
- A notification event sent to the UI each time the operation is done, undone or redone.

## Related Documentation

The application generally uses the API handle classes to work with a design. These handle classes use the commands defined here to modify the design.