2.5.2.6 EDIT Command
  The EDIT command replaces text in the current program
  with text you supply in the command. If you type EDIT
  with no argument, BASIC invokes a text editor and reads the
  current program into the editor's buffer.

  Table 2-2 shows examples of editing in line mode.

  Entering EDIT with no argument instructs VAX BASIC to
  save your program temporarily in a file called BASEDITMP.BAS.
  The editor is then invoked and you can edit the program.
  Exiting from the editor causes the changed program to be-
  come the current program. VAX BASIC then displays the
  Ready prompt.

  VAX BASIC supports the following callable text editors:

  .
        VAX EDT
  .
        VAX Text Processing Utility (VAXTPU)
  .
        VAX Language-Sensitive Editor (LSE)

  The default editor for BASIC is EDT. In DCL, you can over-
  ride this default by defining the logical name BASIC$EDIT.
  To find out if a system assignment exists, enter the following
  DCL command:

    $ SHOW LOGICAL BASIC$EDIT
The name you assign to BASIC$EDIT must be in the form
  nnn $EDIT, ( nnn represents the acronym for the editor). For
  example, you can assign LSE to be the default editor with the
  following command:

  $ ASSIGN "LSE$EDIT" BASIC$EDIT
If the translation of BASIC$EDIT does not conform to
  nnn $EDIT, BASIC creates a temporary file containing your
  source code and spawns a subprocess. BASIC passes the
  translation of BASIC$EDIT to the subprocess.