/MODIFY

 /MODIFY    (default)
 /NOMODIFY

 Determines whether you can modify the main (or first) buffer.  If you
 specify multiple input files on the EDIT/TPU command line, this
 qualifier applies to each buffer.  Does not affect other buffers you
 create during the editing session.

 By default, TPU lets the buffer be modified---you can edit text in
 the buffer, and exiting writes out the buffer to a file, if the
 buffer has been modified (unless you used /NOWRITE or /READ_ONLY).
 Use /NOMODIFY to view a file without making any changes.  You can
 then use cursor-movement commands but cannot change the text.  If you
 do not specify /MODIFY or /NOMODIFY, the application is expected to
 determine the default behavior.  For EVE, the main buffer is made
 modifiable (as well as buffers initially created from your input
 files).

 For EVE, using /READ_ONLY or /NOWRITE makes the buffer unmodifiable
 unless you also use /MODIFY.  For example, the following command
 edits a file named PRACTICE.TXT, making the buffer read-only and
 making it modifiable, so you can practice editing or test procedures
 without writing a file:

    $ EDIT/TPU practice.txt /READ_ONLY /MODIFY

 In EVE, the status line shows whether the buffer is unmodifiable.  If
 the buffer is modifiable, the status line shows the mode (insert or
 overstrike).  You can change the modification attribute of the buffer
 during your editing session by using the SET BUFFER command.