In step 3, the system adds the information. However, in extension 3a, the system shows an error message and prompts the user to use a different command (implied - does not add the information). Not adding the information (3a) cannot happen after adding the information (3), so the number should not be 3a.
In step 3, the system adds the information. However, in extension 3a, the system shows an error message and prompts the user to use a different command (implied - does not add the information). Not adding the information (3a) cannot happen after adding the information (3), so the number should not be 3a.