EXEC provides two commands that invoke the default editor: EDIT, to edit an existing file, and CREATE to create a new file. The default editor is determined by the logical name EDITOR:. You can customize the default editor for all your log-in sessions by adding the following line to your LOGIN.CMD file:

@DEFINE EDITOR: SYS:EDIT.EXE 

(You can specify the executable file for any editor you wish to use in place of SYS:EDIT.EXE.)

You can check your current default editor with the command:

@INFORMATION LOGICAL-NAMES EDITOR:

(The TOPS-20 User's Guide also documents a PERUSE command for invoking the default editor, but this feature is not supported on TWENEX.ORG.)