2.4.1-4 Prompting Command Correction

When a command entry is not recognized or inappropriate, users should be prompted to correct, rather than re-enter the command.

Additional Information:
A faulty command should be able to be retained in the command entry area of the display, with the cursor automatically positioned at the incorrect item, with an advisory message describing the problem. It should be possible for the user to correct individual errors without affecting adjacent valid entries.