Invokes a text editor. Unless you have selected a different
    editor by entering the SET EDITOR command, the TPU-based EVE
    editor is invoked. Use your editor to peruse the current message.
    When you are done, enter the appropriate command to quit from
    your selected editor. If you decide to edit the message and want
    to keep a copy of the newly edited message, enter the appropriate
    command to exit (use the EXIT command in EVE) and supply a file
    name.