An upgraded (version 208) desktop file cannot be read in Emacs < 25.
* etc/NEWS: Add an entry about upgrading a desktop file.
* lisp/desktop.el (desktop-file-version): Amend doc string.
(desktop-native-file-version, desktop-io-file-version): new variables.
(desktop-clear): Set desktop-io-file-version to nil.
(desktop-buffer-info): make the presence of the last item on the list
conditional on (>= desktop-io-file-version 208).
(desktop-save): Add extra parameter VERSION to take user's C-u or C-u C-u.
Amend the doc string. Add code to determine the output file version.
(desktop-create-buffer): Set desktop-io-file-version to the input file's
version.
This directory contains the architecture-independent files used by or
with Emacs. This includes some text files of documentation for GNU
Emacs or of interest to Emacs users, and the file of dumped docstrings
for Emacs functions and variables.
COPYRIGHT AND LICENSE INFORMATION FOR IMAGE FILES
File: emacs.icon
Author: Sun Microsystems, Inc
Copyright (C) 1999, 2001-2016 Free Software Foundation, Inc.
License: GNU General Public License version 3 or later (see COPYING)