Invokes a text editor. Unless you have selected a different
editor, the TPU-based EVE editor is invoked. Use the editor to
peruse the last message. When you are done, enter the appropriate
command to quit from your 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 from your editor (use the
EXIT command with the EVE editor) and supply a file name.