Buffer Changed cannot be set. The field is always disabled.

    CHECKED     : When the field shows a check-mark, it indicates that
                  the buffer is currently changed with respect to the
                  file it represents.
    UNCHECKED   : Without check-mark, the field indicates that the buffer
                  representing the file is currently unchanged. Exiting
                  will not cause any changes to be lost.

   NOTE         : The check-mark also functions when no file is associated
                  with the buffer.

MATRIX