SET(ERASE_UNMODIFIABLE)

     Controls whether TPU erases unmodifiable records in response to
     built-ins that delete lines from a buffer.  For example, ERASE_LINE
     only deletes an unmodifiable record if ERASE_UNMODIFIABLE is turned on.
     If ERASE_UNMODIFIABLE is turned off when ERASE_LINE or a similar
     built-in encounters an unmodifiable record, the built-in returns an
     error and does not delete the record.

     SET (ERASE_UNMODIFIABLE) optionally returns an integer (0 or 1)
     indicating whether ERASE_UNMODIFIABLE was turned on before the current
     call was executed.  This makes it easier to return to the previous
     setting later in the program.

  Syntax

     [previous_erase_setting] := SET (ERASE_UNMODIFIABLE, buffer,
                                      {ON | OFF})

  Parameters

      ERASE_UNMODIFIABLE     A keyword indicating that the SET built-in is
                             being used to control whether unmodifiable
                             records are deleted in response to built-ins
                             that erase lines in a buffer.

      buffer                 The buffer for which you want to turn on or
                             turn off erasing of unmodifiable records.

      ON                     Enables erasing of unmodifiable records.

      OFF                    Disables erasing of unmodifiable records.

      previous_erase_setting An integer (1 or 0) indicating whether
                             ERASE_UNMODIFIABLE was turned on before the
                             current call was executed.

  Example

     The following statement turns off erasing of unmodifiable records in
     the current buffer and returns the previous setting of
     ERASE_UNMODIFIABLE:

     old_setting := SET (ERASE_UNMODIFIABLE, CURRENT_BUFFER, OFF);

  Related Topics

     GET_INFO(BUFFER_VARIABLE)          GET_INFO(MARKER_VARIABLE)
     GET_INFO(WINDOW_VARIABLE)          SET(DISPLAY_VALUE)
     SET(RECORD_ATTRIBUTE)              SET(MODIFIABLE)