Merge from origin/emacs-27

05089a4d65 (origin/emacs-27) Tweak wording re constant variables
a1040861f1 Tweak setcar-related wording
751510f865 * lisp/image-mode.el: Add prefix key 's' and reduce depend...
9261a219ec * doc/emacs/windows.texi (Window Convenience): Decribe mor...
e1d42da0d6 Fix mutability glitches reported by Drew Adams
5805df74f5 Improve mutability doc
dca35b31d0 Improve mutability documentation
81e7d7f111 Document that quoting yields constants
5734339f40 * doc/lispref/keymaps.texi (Extended Menu Items, Easy Menu...
14a570afae Remove #' and function quoting from lambda forms in manual
d5ec18c66b * src/regex-emacs.c (re_match_2_internal): Rework comment ...
4df8a61117 Add new node "Image Mode" to Emacs Manual.
d7d5ee6c57 ; Fix a typo in cmdargs.texi (bug#40701)
5e9db48fbe * doc/lispref/display.texi (Customizing Bitmaps): Fix typo.
eebfb72c90 Document constant vs mutable objects better
6c187ed6b0 Improve documentation of 'sort-lines'
52288f4b66 Mention 'spam-stat-process-directory-age' in the documenta...
067b070598 ; Fix some typos and doc issues (bug#40695)

# Conflicts:
#	etc/NEWS

53 files changed, 420 insertions, 301 deletions

diff --git a/ChangeLog.3 b/ChangeLog.3
index c5bc7b3120d..7f6000fc556 100644
--- a/ChangeLog.3
+++ b/ChangeLog.3
@@ -11660,7 +11660,7 @@
         Mention the Emacs exit code in batch mode
 
         * doc/lispref/os.texi (Batch Mode): Mention what the exit code is
-        if an error is signalled (bug#31552).
+        if an error is signaled (bug#31552).
 
 2019-10-12  Kaushal Modi  <kaushal.modi@gmail.com>
 
@@ -15059,7 +15059,7 @@
 
         * lisp/image/exif.el (exif-parse-buffer): New function.
         (exif-orientation): Ditto.
-        (exif-error): New error symbol, and adjust all error signalling to
+        (exif-error): New error symbol, and adjust all error signaling to
         only use that signal.
 
 2019-09-22  Andreas Schwab  <schwab@linux-m68k.org>
@@ -25100,7 +25100,7 @@
 
         * lisp/json.el (json-read): Try to clarify what's returned (bug#34242).
         (json-encode): Refer to `json-read' about what the input is and
-        say what error is signalled.
+        say what error is signaled.
 
 2019-07-09  Lars Ingebrigtsen  <larsi@gnus.org>
 
@@ -26971,7 +26971,7 @@
         help-C-file-name shouldn't error out if we can't find the name
 
         * lisp/help-fns.el (help-C-file-name): Make help-C-file-name
-        return nil instead of signalling an error if we can't find the
+        return nil instead of signaling an error if we can't find the
         file name (bug#17250).
 
 2019-06-26  Stefan Monnier  <monnier@iro.umontreal.ca>
@@ -34107,7 +34107,7 @@
         Remove unused internal function completion-pcm--optimize-pattern
 
         * lisp/minibuffer.el (completion-pcm--optimize-pattern): Remove
-        unused internal function (that signalled a compilation warning).
+        unused internal function (that signaled a compilation warning).
 
 2019-05-16  Stefan Monnier  <monnier@iro.umontreal.ca>
 
@@ -40134,10 +40134,10 @@
 
 2019-03-30  Mattias Engdegård  <mattiase@acm.org>
 
-        Release regexp before signalling overflow error
+        Release regexp before signaling overflow error
 
         * src/search.c (looking_at_1, search_buffer_re): Unfreeze the regexp
-        buffer before signalling a matcher overflow, since the error
+        buffer before signaling a matcher overflow, since the error
         processing may require quite some regexp use as well (Bug#34910).
 
 2019-03-30  Mattias Engdegård  <mattiase@acm.org>
@@ -88604,7 +88604,7 @@
         Tweak Fdocumentation's error for an undefined function
 
         * src/doc.c (Fdocumentation): Restore the pre-25 behavior
-        of signalling a void-function error for an undefined function.
+        of signaling a void-function error for an undefined function.
         This seems cleaner than Emacs 25's "invalid-function: nil" error,
         which was (probably) an unintended consequence of changes to
         Findirect_function.
diff --git a/admin/notes/bug-triage b/admin/notes/bug-triage
index 2974eee1792..87fb471c708 100644
--- a/admin/notes/bug-triage
+++ b/admin/notes/bug-triage
@@ -81,7 +81,7 @@ the ones that are not reproducible on the current release.
 * New bug triage process
 
 The goal of the new bug triage process is similar to the backlog triage process,
-except that the focus is on prioritizing the bug, and making sure it is has
+except that the focus is on prioritizing the bug, and making sure it has
 necessary information for others to act on.
 
 For each new bug, ask the following questions:
diff --git a/doc/emacs/cmdargs.texi b/doc/emacs/cmdargs.texi
index 9303b0b8dd1..2c131165244 100644
--- a/doc/emacs/cmdargs.texi
+++ b/doc/emacs/cmdargs.texi
@@ -340,7 +340,7 @@ initialization file (@pxref{Resources}).
 @opindex --quick
 Start Emacs with minimum customizations.  This is similar to using
 @samp{-q}, @samp{--no-site-file}, @samp{--no-site-lisp},
-@samp{--no-x-resources}, and @samp{--no-splash} together..
+@samp{--no-x-resources}, and @samp{--no-splash} together.
 
 @item -daemon
 @opindex -daemon
diff --git a/doc/emacs/dired.texi b/doc/emacs/dired.texi
index fba4389094f..d5144141803 100644
--- a/doc/emacs/dired.texi
+++ b/doc/emacs/dired.texi
@@ -1416,7 +1416,8 @@ C-c}.
 
   Image-Dired is a facility for browsing image files.  It provides viewing
 the images either as thumbnails or in full size, either inside Emacs
-or through an external viewer.
+or through an external viewer.  This is different from Image mode
+(@pxref{Image Mode}) for visiting an image file in the Emacs buffer.
 
 @kindex C-t d @r{(Image-Dired)}
 @findex image-dired-display-thumbs
diff --git a/doc/emacs/emacs.texi b/doc/emacs/emacs.texi
index 6ef4ca63ae7..60f2be9a513 100644
--- a/doc/emacs/emacs.texi
+++ b/doc/emacs/emacs.texi
@@ -455,7 +455,8 @@ File Handling
 * Remote Files::        Accessing files on other machines.
 * Quoted File Names::   Quoting special characters in file names.
 * File Name Cache::     Completion against a list of files you often use.
-* File Conveniences::   Convenience Features for Finding Files.
+* File Conveniences::   Convenience features for finding files.
+* Image Mode::          Viewing image files.
 * Filesets::            Handling sets of files.
 
 Saving Files
diff --git a/doc/emacs/files.texi b/doc/emacs/files.texi
index a89b16b3f6d..7d57555ce33 100644
--- a/doc/emacs/files.texi
+++ b/doc/emacs/files.texi
@@ -38,7 +38,8 @@ on file directories.
 * Remote Files::        Accessing files on other machines.
 * Quoted File Names::   Quoting special characters in file names.
 * File Name Cache::     Completion against a list of files you often use.
-* File Conveniences::   Convenience Features for Finding Files.
+* File Conveniences::   Convenience features for finding files.
+* Image Mode::          Viewing image files.
 * Filesets::            Handling sets of files.
 @end menu
 
@@ -2088,8 +2089,7 @@ of the cache with the @code{file-cache-display} command.
 @section Convenience Features for Finding Files
 
   In this section, we introduce some convenient facilities for finding
-recently-opened files, reading file names from a buffer, and viewing
-image files.
+recently-opened files, reading file names from a buffer.
 
 @findex recentf-mode
 @vindex recentf-mode
@@ -2108,6 +2108,9 @@ point.  Partial Completion mode offers other features extending
 @code{find-file}, which can be used with @code{ffap}.
 @xref{Completion Options}.
 
+@node Image Mode
+@section Viewing Image Files
+
 @findex image-mode
 @findex image-toggle-display
 @findex image-next-file
diff --git a/doc/emacs/fixit.texi b/doc/emacs/fixit.texi
index 2c268f14fb7..5046146dda6 100644
--- a/doc/emacs/fixit.texi
+++ b/doc/emacs/fixit.texi
@@ -204,8 +204,8 @@ sentences and paragraphs, respectively.  These commands work like
   A numeric argument to a transpose command serves as a repeat count: it
 tells the transpose command to move the character (or word or
 expression or line) before or containing point across several other
-characters (or words or expressions or lines).  For example, @kbd{C-u
-3 C-t} moves the character before point forward across three other
+characters (or words or expressions or lines).  For example, @w{@kbd{C-u
+3 C-t}} moves the character before point forward across three other
 characters.  It would change @samp{f@point{}oobar} into
 @samp{oobf@point{}ar}.  This is equivalent to repeating @kbd{C-t}
 three times.  @kbd{C-u - 4 M-t} moves the word before point backward
@@ -307,10 +307,10 @@ region; @pxref{Disabled Transient Mark}.)
 @cindex spell-checking the active region
   Similarly, the command @kbd{M-x ispell} performs spell-checking in
 the region if one is active, or in the entire buffer otherwise.  The
-commands @kbd{M-x ispell-buffer} and @kbd{M-x ispell-region}
+commands @w{@kbd{M-x ispell-buffer}} and @w{@kbd{M-x ispell-region}}
 explicitly perform spell-checking on the entire buffer or the region
 respectively.  To check spelling in an email message you are writing,
-use @kbd{M-x ispell-message}; that command checks the whole buffer,
+use @w{@kbd{M-x ispell-message}}; that command checks the whole buffer,
 except for material that is indented or appears to be cited from other
 messages.  @xref{Sending Mail}.
 
@@ -368,8 +368,8 @@ wildcard.
 @item C-g
 @itemx X
 Quit interactive spell-checking, leaving point at the word that was
-being checked.  You can restart checking again afterward with @kbd{C-u
-M-$}.
+being checked.  You can restart checking again afterward with @w{@kbd{C-u
+M-$}}.
 
 @item x
 Quit interactive spell-checking and move point back to where it was
@@ -387,8 +387,8 @@ Show the list of options.
 (@code{ispell-complete-word}) performs in-buffer completion based on
 spelling correction.  Insert the beginning of a word, and then type
 @kbd{M-@key{TAB}}; this shows a list of completions.  (If your
-window manager intercepts @kbd{M-@key{TAB}}, type @kbd{@key{ESC}
-@key{TAB}} or @kbd{C-M-i}.)  Each completion is listed with a digit or
+window manager intercepts @kbd{M-@key{TAB}}, type @w{@kbd{@key{ESC}
+@key{TAB}}} or @kbd{C-M-i}.)  Each completion is listed with a digit or
 character; type that digit or character to choose it.
 
 @cindex @code{ispell} program
@@ -396,7 +396,7 @@ character; type that digit or character to choose it.
   Once started, the spell-checker subprocess continues
 to run, waiting for something to do, so that subsequent spell-checking
 commands complete more quickly.  If you want to get rid of the
-process, use @kbd{M-x ispell-kill-ispell}.  This is not usually
+process, use @w{@kbd{M-x ispell-kill-ispell}}.  This is not usually
 necessary, since the process uses no processor time except when you do
 spelling correction.
 
@@ -409,7 +409,7 @@ the standard dictionary and your personal dictionary.  The standard
 dictionary is specified by the variable @code{ispell-local-dictionary}
 or, if that is @code{nil}, by the variable @code{ispell-dictionary}.
 If both are @code{nil}, the spelling program's default dictionary is
-used.  The command @kbd{M-x ispell-change-dictionary} sets the
+used.  The command @w{@kbd{M-x ispell-change-dictionary}} sets the
 standard dictionary for the buffer and then restarts the subprocess,
 so that it will use a different standard dictionary.  Your personal
 dictionary is specified by the variable
@@ -431,8 +431,8 @@ dictionary.
 @findex flyspell-mode
   Flyspell mode is a minor mode that performs automatic spell-checking
 of the text you type as you type it.  When it finds a word that it
-does not recognize, it highlights that word.  Type @kbd{M-x
-flyspell-mode} to toggle Flyspell mode in the current buffer.  To
+does not recognize, it highlights that word.  Type @w{@kbd{M-x
+flyspell-mode}} to toggle Flyspell mode in the current buffer.  To
 enable Flyspell mode in all text mode buffers, add
 @code{flyspell-mode} to @code{text-mode-hook}.  @xref{Hooks}.  Note
 that, as Flyspell mode needs to check each word across which you move,
@@ -448,14 +448,14 @@ it with @kbd{mouse-2} (@code{flyspell-correct-word}) to display a menu
 of possible corrections and actions.  In addition, @kbd{C-.} or
 @kbd{@key{ESC}-@key{TAB}} (@code{flyspell-auto-correct-word}) will
 propose various successive corrections for the word at point, and
-@kbd{C-c $} (@code{flyspell-correct-word-before-point}) will pop up a
+@w{@kbd{C-c $}} (@code{flyspell-correct-word-before-point}) will pop up a
 menu of possible corrections.  Of course, you can always correct the
 misspelled word by editing it manually in any way you like.
 
 @findex flyspell-prog-mode
   Flyspell Prog mode works just like ordinary Flyspell mode, except
 that it only checks words in comments and string constants.  This
-feature is useful for editing programs.  Type @kbd{M-x
-flyspell-prog-mode} to enable or disable this mode in the current
+feature is useful for editing programs.  Type @w{@kbd{M-x
+flyspell-prog-mode}} to enable or disable this mode in the current
 buffer.  To enable this mode in all programming mode buffers, add
 @code{flyspell-prog-mode} to @code{prog-mode-hook} (@pxref{Hooks}).
diff --git a/doc/emacs/frames.texi b/doc/emacs/frames.texi
index 7a583b96bbd..94218424d37 100644
--- a/doc/emacs/frames.texi
+++ b/doc/emacs/frames.texi
@@ -227,8 +227,9 @@ left.  If you'd like to reverse the direction of horizontal scrolling,
 customize the variable @code{mouse-wheel-flip-direction} to a
 non-@code{nil} value.
 
-When the mouse pointer is over an image, scrolling the mouse wheel
-with the @key{Ctrl} modifier scales the image under the mouse pointer.
+When the mouse pointer is over an image in Image mode, @pxref{Image Mode},
+scrolling the mouse wheel with the @key{Ctrl} modifier scales the image
+under the mouse pointer.
 
 
 @node Word and Line Mouse
diff --git a/doc/emacs/misc.texi b/doc/emacs/misc.texi
index 294430aa183..a15aa17a66f 100644
--- a/doc/emacs/misc.texi
+++ b/doc/emacs/misc.texi
@@ -2883,7 +2883,7 @@ if there is an active region (@pxref{Mark}), the default URL comes
 from the region instead, after removing any whitespace from it.  The
 command then creates a new buffer with the embedded browser showing
 the specified URL.  The buffer is put in the Xwidget-WebKit mode
-(similar to Image mode, @pxref{File Conveniences}), which provides
+(similar to Image mode, @pxref{Image Mode}), which provides
 one-key commands for scrolling the widget, changing its size, and
 reloading it.  Type @w{@kbd{C-h b}} in that buffer to see the key
 bindings.
diff --git a/doc/emacs/windows.texi b/doc/emacs/windows.texi
index 2e07a98f57d..910ef8fd88d 100644
--- a/doc/emacs/windows.texi
+++ b/doc/emacs/windows.texi
@@ -586,13 +586,25 @@ buffer.  @xref{Follow Mode}.
 @cindex directional window selection
 @findex windmove-right
 @findex windmove-default-keybindings
+@findex windmove-display-default-keybindings
+@findex windmove-delete-default-keybindings
+@findex windmove-swap-states-in-direction
   The Windmove package defines commands for moving directionally
 between neighboring windows in a frame.  @kbd{M-x windmove-right}
 selects the window immediately to the right of the currently selected
-one, and similarly for the left, up, and down
-counterparts.  @w{@kbd{M-x windmove-default-keybindings}} binds these
-commands to @kbd{S-right} etc.; doing so disables shift selection for
-those keys (@pxref{Shift Selection}).
+one, and similarly for the left, up, and down counterparts.
+@w{@kbd{M-x windmove-default-keybindings}} binds these commands to
+@kbd{S-right} etc.; doing so disables shift selection for those keys
+(@pxref{Shift Selection}).  In the same way as keybindings can be
+defined for commands that select windows directionally, you can use
+@w{@kbd{M-x windmove-display-default-keybindings}} to define
+keybindings for commands that specify in what direction to display the
+window for the buffer that the next command is going to display.
+Also there is @w{@kbd{M-x windmove-delete-default-keybindings}} to
+define keybindings for commands that delete windows directionally, and
+@w{@kbd{M-x windmove-swap-states-in-direction}} that define
+keybindings for commands that swap the window contents of the selected
+window with the window in the specified direction.
 
   The command @kbd{M-x compare-windows} lets you compare the text
 shown in different windows.  @xref{Comparing Files}.
diff --git a/doc/lispintro/emacs-lisp-intro.texi b/doc/lispintro/emacs-lisp-intro.texi
index 1726936de10..7484ce57607 100644
--- a/doc/lispintro/emacs-lisp-intro.texi
+++ b/doc/lispintro/emacs-lisp-intro.texi
@@ -2329,7 +2329,7 @@ area.
 
 @cindex @samp{bind} defined
 There are several ways by which a variable can be given a value.  One of
-the ways is to use either the function @code{set} or the function
+the ways is to use either the function @code{set} or the special form
 @code{setq}.  Another way is to use @code{let} (@pxref{let}).  (The
 jargon for this process is to @dfn{bind} a variable to a value.)
 
@@ -4517,7 +4517,7 @@ number; it will be printed as the character with that @sc{ascii} code.
 
 @item setq
 @itemx set
-The @code{setq} function sets the value of its first argument to the
+The @code{setq} special form sets the value of its first argument to the
 value of the second argument.  The first argument is automatically
 quoted by @code{setq}.  It does the same for succeeding pairs of
 arguments.  Another function, @code{set}, takes only two arguments and
@@ -7317,11 +7317,21 @@ which leave the original list as it was.  One way to find out how this
 works is to experiment.  We will start with the @code{setcar} function.
 
 @need 1200
+@cindex constant lists
+@cindex mutable lists
 First, we can make a list and then set the value of a variable to the
-list, using the @code{setq} function.  Here is a list of animals:
+list, using the @code{setq} special form.  Because we intend to use
+@code{setcar} to change the list, this @code{setq} should not use the
+quoted form @code{'(antelope giraffe lion tiger)}, as that would yield
+a list that is part of the program and bad things could happen if we
+tried to change part of the program while running it.  Generally
+speaking an Emacs Lisp program's components should be constant (or
+unchanged) while the program is running.  So we instead construct an
+animal list that is @dfn{mutable} (or changeable) by using the
+@code{list} function, as follows:
 
 @smallexample
-(setq animals '(antelope giraffe lion tiger))
+(setq animals (list 'antelope 'giraffe 'lion 'tiger))
 @end smallexample
 
 @noindent
@@ -7398,7 +7408,7 @@ To see how this works, set the value of the variable to a list of
 domesticated animals by evaluating the following expression:
 
 @smallexample
-(setq domesticated-animals '(horse cow sheep goat))
+(setq domesticated-animals (list 'horse 'cow 'sheep 'goat))
 @end smallexample
 
 @need 1200
@@ -8846,7 +8856,7 @@ and then find the value of @code{trees}:
 
 @smallexample
 @group
-(setq trees '(maple oak pine birch))
+(setq trees (list 'maple 'oak 'pine 'birch))
      @result{} (maple oak pine birch)
 @end group
 
@@ -9366,7 +9376,7 @@ For example:
 
 @smallexample
 @group
-(setq triple '(1 2 3))
+(setq triple (list 1 2 3))
 
 (setcar triple '37)
 
@@ -9547,7 +9557,7 @@ part of which is the address of the next pair.  The very last box
 points to the symbol @code{nil}, which marks the end of the list.
 
 @need 1200
-When a variable is set to a list with a function such as @code{setq},
+When a variable is set to a list with an operation such as @code{setq},
 it stores the address of the first box in the variable.  Thus,
 evaluation of the expression
 
@@ -17092,7 +17102,7 @@ reminders.
 
 @cindex Mail aliases
 @noindent
-This @code{setq} command sets the value of the variable
+This @code{setq} sets the value of the variable
 @code{mail-aliases} to @code{t}.  Since @code{t} means true, the line
 says, in effect, ``Yes, use mail aliases.''
 
@@ -17130,8 +17140,8 @@ The following turns off Indent Tabs mode:
 @end smallexample
 
 Note that this line uses @code{setq-default} rather than the
-@code{setq} command that we have seen before.  The @code{setq-default}
-command sets values only in buffers that do not have their own local
+@code{setq} that we have seen before; @code{setq-default}
+sets values only in buffers that do not have their own local
 values for the variable.
 
 @ifinfo
diff --git a/doc/lispref/abbrevs.texi b/doc/lispref/abbrevs.texi
index 6689b560c78..575be187d3f 100644
--- a/doc/lispref/abbrevs.texi
+++ b/doc/lispref/abbrevs.texi
@@ -370,9 +370,9 @@ definitions of @code{local-abbrev-table} and @code{text-mode-abbrev-table}.
       (funcall expand))))
 
 (add-hook 'foo-mode-hook
-          #'(lambda ()
-              (add-function :around (local 'abbrev-expand-function)
-                            #'foo-mode-abbrev-expand-function)))
+          (lambda ()
+            (add-function :around (local 'abbrev-expand-function)
+                          #'foo-mode-abbrev-expand-function)))
 @end smallexample
 
 @node Standard Abbrev Tables
diff --git a/doc/lispref/backups.texi b/doc/lispref/backups.texi
index b7318a99b8f..4ed1a10fcf6 100644
--- a/doc/lispref/backups.texi
+++ b/doc/lispref/backups.texi
@@ -807,7 +807,7 @@ If you just want to automatically auto-revert every
 
 @example
 (setq-local buffer-stale-function
-     #'(lambda (&optional noconfirm) 'fast))
+     (lambda (&optional noconfirm) 'fast))
 @end example
 
 @noindent
diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 132a3c85354..e01cfedc4b8 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -4358,7 +4358,7 @@ height.
 @end defun
 
 @defun destroy-fringe-bitmap bitmap
-This function destroy the fringe bitmap identified by @var{bitmap}.
+This function destroys the fringe bitmap identified by @var{bitmap}.
 If @var{bitmap} identifies a standard fringe bitmap, it actually
 restores the standard definition of that bitmap, instead of
 eliminating it entirely.
@@ -6926,7 +6926,7 @@ end of the buffer continues from the other end.  If
 is displayed.  Any button with a non-@code{nil} @code{skip} property
 is skipped over.  Returns the button found, and signals an error if no
 buttons can be found.  If @var{no-error} in non-@code{nil}, return nil
-instead of signalling the error.
+instead of signaling the error.
 @end deffn
 
 @deffn Command backward-button n &optional wrap display-message
@@ -6938,7 +6938,7 @@ end of the buffer continues from the other end.  If
 is displayed.  Any button with a non-@code{nil} @code{skip} property
 is skipped over.  Returns the button found, and signals an error if no
 buttons can be found.  If @var{no-error} in non-@code{nil}, return nil
-instead of signalling the error.
+instead of signaling the error.
 @end deffn
 
 @defun next-button pos &optional count-current
diff --git a/doc/lispref/edebug.texi b/doc/lispref/edebug.texi
index cfef5c12d1e..5970e7cf801 100644
--- a/doc/lispref/edebug.texi
+++ b/doc/lispref/edebug.texi
@@ -858,7 +858,7 @@ to a non-@code{nil} value.
   Here is an example of code that creates a circular structure:
 
 @example
-(setq a '(x y))
+(setq a (list 'x 'y))
 (setcar a a)
 @end example
 
diff --git a/doc/lispref/elisp.texi b/doc/lispref/elisp.texi
index cfd96f7aa68..bba1b63115f 100644
--- a/doc/lispref/elisp.texi
+++ b/doc/lispref/elisp.texi
@@ -297,6 +297,7 @@ Lisp Data Types
 * Circular Objects::        Read syntax for circular structure.
 * Type Predicates::         Tests related to types.
 * Equality Predicates::     Tests of equality between any two objects.
+* Constants and Mutability::  Whether an object's value can change.
 
 Programming Types
 
diff --git a/doc/lispref/eval.texi b/doc/lispref/eval.texi
index f6f36ed3427..021604c5142 100644
--- a/doc/lispref/eval.texi
+++ b/doc/lispref/eval.texi
@@ -158,6 +158,12 @@ contents unchanged.
 @end group
 @end example
 
+  A self-evaluating form yields constant conses, vectors and strings, and you
+should not attempt to modify their contents via @code{setcar}, @code{aset} or
+similar operations.  The Lisp interpreter might unify the constants
+yielded by your program's self-evaluating forms, so that these
+constants might share structure.  @xref{Constants and Mutability}.
+
   It is common to write numbers, characters, strings, and even vectors
 in Lisp code, taking advantage of the fact that they self-evaluate.
 However, it is quite unusual to do this for types that lack a read
@@ -558,6 +564,8 @@ and vectors.)
 
 @defspec quote object
 This special form returns @var{object}, without evaluating it.
+The returned value is a constant, and should not be modified.
+@xref{Constants and Mutability}.
 @end defspec
 
 @cindex @samp{'} for quoting
@@ -612,10 +620,12 @@ only part of a list, while computing and substituting other parts.
 
   @dfn{Backquote constructs} allow you to quote a list, but
 selectively evaluate elements of that list.  In the simplest case, it
-is identical to the special form @code{quote}
+is identical to the special form
 @iftex
+@code{quote}.
 @end iftex
 @ifnottex
+@code{quote}
 (described in the previous section; @pxref{Quoting}).
 @end ifnottex
 For example, these two forms yield identical results:
@@ -693,6 +703,9 @@ Here are some examples:
 @end group
 @end example
 
+If a subexpression of a backquote construct has no substitutions or
+splices, it acts like @code{quote} in that it yields constant conses,
+vectors and strings that should not be modified.
 
 @node Eval
 @section Eval
diff --git a/doc/lispref/functions.texi b/doc/lispref/functions.texi
index 5cf67ba6473..bc8ec0ef1b0 100644
--- a/doc/lispref/functions.texi
+++ b/doc/lispref/functions.texi
@@ -970,7 +970,7 @@ string.
 @end group
 
 @group
-(mapconcat (function (lambda (x) (format "%c" (1+ x))))
+(mapconcat (lambda (x) (format "%c" (1+ x)))
            "HAL-8000"
            "")
      @result{} "IBM.9111"
@@ -2287,7 +2287,7 @@ function) as a generalized variable.  @var{setter} can be a symbol in which
 case it will be passed to @code{gv-define-simple-setter}, or it can be of the
 form @code{(lambda (@var{arg}) @var{body})} in which case that function will
 additionally have access to the macro (or function)'s arguments and it will
-passed to @code{gv-define-setter}.
+be passed to @code{gv-define-setter}.
 
 @end table
 
diff --git a/doc/lispref/help.texi b/doc/lispref/help.texi
index eea1fd2e8f1..9b3c4fcb23d 100644
--- a/doc/lispref/help.texi
+++ b/doc/lispref/help.texi
@@ -175,49 +175,47 @@ All symbols that have PATTERN in their name are described
 in the *Help* buffer."
   (interactive "sDescribe symbols matching: ")
   (let ((describe-func
-         (function
-          (lambda (s)
+         (lambda (s)
 @end group
 @group
-            ;; @r{Print description of symbol.}
-            (if (fboundp s)             ; @r{It is a function.}
-                (princ
-                 (format "%s\t%s\n%s\n\n" s
-                   (if (commandp s)
-                       (let ((keys (where-is-internal s)))
-                         (if keys
-                             (concat
-                              "Keys: "
-                              (mapconcat 'key-description
-                                         keys " "))
-                           "Keys: none"))
-                     "Function")
+           ;; @r{Print description of symbol.}
+           (if (fboundp s)             ; @r{It is a function.}
+               (princ
+                (format "%s\t%s\n%s\n\n" s
+                  (if (commandp s)
+                      (let ((keys (where-is-internal s)))
+                        (if keys
+                            (concat
+                             "Keys: "
+                             (mapconcat 'key-description
+                                        keys " "))
+                          "Keys: none"))
+                    "Function")
 @end group
 @group
-                   (or (documentation s)
-                       "not documented"))))
+                  (or (documentation s)
+                      "not documented"))))
 
-            (if (boundp s)              ; @r{It is a variable.}
+           (if (boundp s)              ; @r{It is a variable.}
 @end group
 @group
-                (princ
-                 (format "%s\t%s\n%s\n\n" s
-                   (if (custom-variable-p s)
-                       "Option " "Variable")
+               (princ
+                (format "%s\t%s\n%s\n\n" s
+                  (if (custom-variable-p s)
+                      "Option " "Variable")
 @end group
 @group
-                   (or (documentation-property
-                         s 'variable-documentation)
-                       "not documented")))))))
+                  (or (documentation-property
+                        s 'variable-documentation)
+                      "not documented"))))))
         sym-list)
 @end group
 
 @group
     ;; @r{Build a list of symbols that match pattern.}
-    (mapatoms (function
-               (lambda (sym)
-                 (if (string-match pattern (symbol-name sym))
-                     (setq sym-list (cons sym sym-list))))))
+    (mapatoms (lambda (sym)
+                (if (string-match pattern (symbol-name sym))
+                    (setq sym-list (cons sym sym-list)))))
 @end group
 
 @group
diff --git a/doc/lispref/keymaps.texi b/doc/lispref/keymaps.texi
index 2c90d208c02..130ff0d8671 100644
--- a/doc/lispref/keymaps.texi
+++ b/doc/lispref/keymaps.texi
@@ -1441,10 +1441,10 @@ Here is an example showing a keymap before and after substitution:
 
 @smallexample
 @group
-(setq map '(keymap
-            (?1 . olddef-1)
-            (?2 . olddef-2)
-            (?3 . olddef-1)))
+(setq map (list 'keymap
+                (cons ?1 olddef-1)
+                (cons ?2 olddef-2)
+                (cons ?3 olddef-1)))
 @result{} (keymap (49 . olddef-1) (50 . olddef-2) (51 . olddef-1))
 @end group
 
@@ -2226,14 +2226,11 @@ right value for selecting that button.  Clicking on the button should
 set the variable so that the button you clicked on becomes selected.
 
 @item :key-sequence @var{key-sequence}
-This property specifies which key sequence is likely to be bound to the
-same command invoked by this menu item.  If you specify a correct key
-sequence, that sequence will be preferred over others.
-
-If you specify an incorrect key sequence, it has no effect; before Emacs
-displays @var{key-sequence} in the menu, it verifies that
-@var{key-sequence} is really equivalent to this menu item.  Specifying
-@code{nil} for @var{key-sequence} is equivalent to the
+This property specifies which key sequence to display as keyboard equivalent.
+Before Emacs displays @var{key-sequence} in the menu, it verifies that
+@var{key-sequence} is really equivalent to this menu item, so it only
+has an effect if you specify a correct key sequence.
+Specifying @code{nil} for @var{key-sequence} is equivalent to the
 @code{:key-sequence} attribute being absent.
 
 @item :keys @var{string}
@@ -2916,17 +2913,17 @@ the following:
 
 @table @code
 @item :keys @var{keys}
-@var{keys} is a keyboard equivalent to the menu item (a string).  This
-is normally not needed, as keyboard equivalents are computed
+@var{keys} is a string to display as keyboard equivalent to the menu item.
+This is normally not needed, as keyboard equivalents are computed
 automatically.  @var{keys} is expanded with
 @code{substitute-command-keys} before it is displayed (@pxref{Keys in
 Documentation}).
 
 @item :key-sequence @var{keys}
-@var{keys} is a hint for speeding up Emacs's first display of the
-menu.  It should be @code{nil} if you know that the menu item has no keyboard
-equivalent; otherwise it should be a string or vector specifying a
-keyboard equivalent for the menu item.
+@var{keys} is a hint indicating which key sequence to display as
+keyboard equivalent, in case the command is bound to several key sequences.
+It has no effect if @var{keys} is not bound to same command as this
+menu item.
 
 @item :active @var{enable}
 @var{enable} is an expression; if it evaluates to @code{nil}, the item
diff --git a/doc/lispref/lists.texi b/doc/lispref/lists.texi
index 27fa5385e35..1125af7bec3 100644
--- a/doc/lispref/lists.texi
+++ b/doc/lispref/lists.texi
@@ -866,10 +866,15 @@ foo                       ;; @r{@code{foo} was changed.}
 @node Modifying Lists
 @section Modifying Existing List Structure
 @cindex destructive list operations
+@cindex mutable lists
 
   You can modify the @sc{car} and @sc{cdr} contents of a cons cell with the
 primitives @code{setcar} and @code{setcdr}.  These are destructive
 operations because they change existing list structure.
+Destructive operations should be applied only to mutable lists,
+that is, lists constructed via @code{cons}, @code{list} or similar
+operations.  Lists created by quoting are constants and should not be
+changed by destructive operations.  @xref{Constants and Mutability}.
 
 @cindex CL note---@code{rplaca} vs @code{setcar}
 @quotation
@@ -906,7 +911,7 @@ value @var{object}.  For example:
 
 @example
 @group
-(setq x '(1 2))
+(setq x (list 1 2))  ; @r{Create a mutable list.}
      @result{} (1 2)
 @end group
 @group
@@ -926,8 +931,8 @@ these lists.  Here is an example:
 
 @example
 @group
-;; @r{Create two lists that are partly shared.}
-(setq x1 '(a b c))
+;; @r{Create two mutable lists that are partly shared.}
+(setq x1 (list 'a 'b 'c))
      @result{} (a b c)
 (setq x2 (cons 'z (cdr x1)))
      @result{} (z b c)
@@ -1017,11 +1022,11 @@ reached via the @sc{cdr}.
 
 @example
 @group
-(setq x '(1 2 3))
+(setq x (list 1 2 3))  ; @r{Create a mutable list.}
      @result{} (1 2 3)
 @end group
 @group
-(setcdr x '(4))
+(setcdr x '(4))  ; @r{Modify the list's tail to be a constant list.}
      @result{} (4)
 @end group
 @group
@@ -1037,7 +1042,7 @@ the @sc{cdr} of the first cons cell:
 
 @example
 @group
-(setq x1 '(a b c))
+(setq x1 (list 'a 'b 'c))
      @result{} (a b c)
 (setcdr x1 (cdr (cdr x1)))
      @result{} (c)
@@ -1069,7 +1074,7 @@ of this list.
 
 @example
 @group
-(setq x1 '(a b c))
+(setq x1 (list 'a 'b 'c))
      @result{} (a b c)
 (setcdr x1 (cons 'd (cdr x1)))
      @result{} (d b c)
@@ -1130,11 +1135,11 @@ Unlike @code{append} (@pxref{Building Lists}), the @var{lists} are
 
 @example
 @group
-(setq x '(1 2 3))
+(setq x (list 1 2 3))  ; @r{Create a mutable list.}
      @result{} (1 2 3)
 @end group
 @group
-(nconc x '(4 5))
+(nconc x '(4 5))  ; @r{Modify the list's tail to be a constant list.}
      @result{} (1 2 3 4 5)
 @end group
 @group
@@ -1150,7 +1155,7 @@ list:
 
 @example
 @group
-(setq x '(1 2 3))
+(setq x (list 1 2 3))
      @result{} (1 2 3)
 @end group
 @group
@@ -1163,11 +1168,13 @@ x
 @end group
 @end example
 
-However, the other arguments (all but the last) must be lists.
+However, the other arguments (all but the last) should be mutable lists.
 
-A common pitfall is to use a quoted constant list as a non-last
-argument to @code{nconc}.  If you do this, your program will change
-each time you run it!  Here is what happens:
+A common pitfall is to use a constant list as a non-last
+argument to @code{nconc}.  If you do this, the resulting behavior
+is undefined.  It is possible that your program will change
+each time you run it!  Here is what might happen (though this
+is not guaranteed to happen):
 
 @smallexample
 @group
@@ -1270,7 +1277,7 @@ removing it involves changing the @sc{cdr}s (@pxref{Setcdr}).
 
 @example
 @group
-(setq sample-list '(a b c (4)))
+(setq sample-list (list 'a 'b 'c '(4)))
      @result{} (a b c (4))
 @end group
 @group
@@ -1303,12 +1310,12 @@ into the variable that held the original list:
 (setq flowers (delq 'rose flowers))
 @end example
 
-In the following example, the @code{(4)} that @code{delq} attempts to match
-and the @code{(4)} in the @code{sample-list} are not @code{eq}:
+In the following example, the @code{(list 4)} that @code{delq} attempts to match
+and the @code{(4)} in the @code{sample-list} are @code{equal} but not @code{eq}:
 
 @example
 @group
-(delq '(4) sample-list)
+(delq (list 4) sample-list)
      @result{} (a c (4))
 @end group
 @end example
@@ -1324,7 +1331,7 @@ of @code{list}.
 
 @example
 @group
-(setq sample-list '(a b c a b c))
+(setq sample-list (list 'a 'b 'c 'a 'b 'c))
      @result{} (a b c a b c)
 @end group
 @group
@@ -1349,12 +1356,12 @@ Compare this with @code{memq}:
 
 @example
 @group
-(memql 1.2 '(1.1 1.2 1.3))  ; @r{@code{1.2} and @code{1.2} are @code{eql}.}
+(memql 1.2 '(1.1 1.2 1.3))  ; @r{@code{1.2} and @code{1.2} must be @code{eql}.}
      @result{} (1.2 1.3)
 @end group
 @group
-(memq 1.2 '(1.1 1.2 1.3))  ; @r{@code{1.2} and @code{1.2} are not @code{eq}.}
-     @result{} nil
+(memq 1.2 '(1.1 1.2 1.3))  ; @r{@code{1.2} and @code{1.2} need not be @code{eq}.}
+     @result{} nil         ; @r{... or it might be @code{(1.2 1.3)}.}
 @end group
 @end example
 @end defun
@@ -1373,11 +1380,11 @@ Compare this with @code{memq}:
 
 @example
 @group
-(member '(2) '((1) (2)))  ; @r{@code{(2)} and @code{(2)} are @code{equal}.}
+(member (list 2) '((1) (2)))  ; @r{@code{(list 2)} and @code{(2)} are @code{equal}.}
      @result{} ((2))
 @end group
 @group
-(memq '(2) '((1) (2)))    ; @r{@code{(2)} and @code{(2)} are not @code{eq}.}
+(memq (list 2) '((1) (2)))    ; @r{@code{(list 2)} and @code{(2)} are not @code{eq}.}
      @result{} nil
 @end group
 @group
@@ -1407,7 +1414,7 @@ For example:
 
 @example
 @group
-(setq l '((2) (1) (2)))
+(setq l (list '(2) '(1) '(2)))
 (delete '(2) l)
      @result{} ((1))
 l
@@ -1416,7 +1423,7 @@ l
 ;; @r{write @code{(setq l (delete '(2) l))}.}
 @end group
 @group
-(setq l '((2) (1) (2)))
+(setq l (list '(2) '(1) '(2)))
 (delete '(1) l)
      @result{} ((2) (2))
 l
@@ -1618,9 +1625,10 @@ keys may not be symbols:
       '(("simple leaves" . oak)
         ("compound leaves" . horsechestnut)))
 
-(assq "simple leaves" leaves)
+;; @r{The @code{copy-sequence} means the keys are not @code{eq}.}
+(assq (copy-sequence "simple leaves") leaves)
      @result{} nil
-(assoc "simple leaves" leaves)
+(assoc (copy-sequence "simple leaves") leaves)
      @result{} ("simple leaves" . oak)
 @end smallexample
 @end defun
@@ -1759,7 +1767,7 @@ correct results, use the return value of @code{assq-delete-all} rather
 than looking at the saved value of @var{alist}.
 
 @example
-(setq alist '((foo 1) (bar 2) (foo 3) (lose 4)))
+(setq alist (list '(foo 1) '(bar 2) '(foo 3) '(lose 4)))
      @result{} ((foo 1) (bar 2) (foo 3) (lose 4))
 (assq-delete-all 'foo alist)
      @result{} ((bar 2) (lose 4))
@@ -1926,7 +1934,7 @@ function returns the modified property list, so you can store that back
 in the place where you got @var{plist}.  For example,
 
 @example
-(setq my-plist '(bar t foo 4))
+(setq my-plist (list 'bar t 'foo 4))
      @result{} (bar t foo 4)
 (setq my-plist (plist-put my-plist 'foo 69))
      @result{} (bar t foo 69)
diff --git a/doc/lispref/objects.texi b/doc/lispref/objects.texi
index 855dff2130a..3e9f2221020 100644
--- a/doc/lispref/objects.texi
+++ b/doc/lispref/objects.texi
@@ -46,6 +46,10 @@ you store in it, type and all.  (Actually, a small number of Emacs
 Lisp variables can only take on values of a certain type.
 @xref{Variables with Restricted Values}.)
 
+  Some Lisp objects are @dfn{constant}: their values never change.
+Others are @dfn{mutable}: their values can be changed via destructive
+operations that involve side effects.
+
   This chapter describes the purpose, printed representation, and read
 syntax of each of the standard types in GNU Emacs Lisp.  Details on how
 to use these types can be found in later chapters.
@@ -59,6 +63,7 @@ to use these types can be found in later chapters.
 * Circular Objects::            Read syntax for circular structure.
 * Type Predicates::             Tests related to types.
 * Equality Predicates::         Tests of equality between any two objects.
+* Constants and Mutability::    Whether an object's value can change.
 @end menu
 
 @node Printed Representation
@@ -2377,3 +2382,46 @@ that for two strings to be equal, they have the same text properties.
 @end group
 @end example
 @end defun
+
+@node Constants and Mutability
+@section Constants and Mutability
+@cindex constants
+@cindex mutable objects
+
+  Some Lisp objects are constant: their values never change.
+For example, you can create a new integer by calculating one, but you
+cannot modify the value of an existing integer.
+
+  Other Lisp objects are mutable: their values can be changed
+via destructive operations involving side effects.  For example, an
+existing marker can be changed by moving the marker to point to
+somewhere else.
+
+  Although numbers are always constants and markers are always
+mutable, some types contain both constant and mutable members.  These
+types include conses, vectors, strings, and symbols.  For example, the string
+literal @code{"aaa"} yields a constant string, whereas the function
+call @code{(make-string 3 ?a)} yields a mutable string that can be
+changed via later calls to @code{aset}.
+
+  Trying to modify a constant variable signals an error
+(@pxref{Constant Variables}).
+A program should not attempt to modify other types of constants because the
+resulting behavior is undefined: the Lisp interpreter might or might
+not detect the error, and if it does not detect the error the
+interpreter can behave unpredictably thereafter.  Another way to put
+this is that although mutable objects are safe to change and constant
+symbols reliably reject attempts to change them, other constants are
+not safely mutable: if you try to change one your program might
+behave as you expect but it might crash or worse.  This problem occurs
+with types that have both constant and mutable members, and that have
+mutators like @code{setcar} and @code{aset} that are valid on mutable
+objects but hazardous on constants.
+
+  When the same constant occurs multiple times in a program, the Lisp
+interpreter might save time or space by reusing existing constants or
+constant components.  For example, @code{(eq "abc" "abc")} returns
+@code{t} if the interpreter creates only one instance of the string
+constant @code{"abc"}, and returns @code{nil} if it creates two
+instances.  Lisp programs should be written so that they work
+regardless of whether this optimization is in use.
diff --git a/doc/lispref/os.texi b/doc/lispref/os.texi
index e72858bbf1a..5c0b1e2edf0 100644
--- a/doc/lispref/os.texi
+++ b/doc/lispref/os.texi
@@ -2617,7 +2617,7 @@ if it is non-@code{nil}; this can be overridden by binding
 This variable is non-@code{nil} when Emacs is running in batch mode.
 @end defvar
 
-If Emacs exits due to signalling an error in batch mode, the exit
+If Emacs exits due to signaling an error in batch mode, the exit
 status of the Emacs command is non-zero:
 
 @example
diff --git a/doc/lispref/sequences.texi b/doc/lispref/sequences.texi
index 1a3a04f680b..1cb0d05cc7b 100644
--- a/doc/lispref/sequences.texi
+++ b/doc/lispref/sequences.texi
@@ -183,11 +183,11 @@ for other ways to copy sequences.
 
 @example
 @group
-(setq bar '(1 2))
+(setq bar (list 1 2))  ; @r{Create a mutable list.}
      @result{} (1 2)
 @end group
 @group
-(setq x (vector 'foo bar))
+(setq x (vector 'foo bar))  ; @r{Create a mutable vector.}
      @result{} [foo (1 2)]
 @end group
 @group
@@ -278,7 +278,7 @@ Unlike @code{reverse} the original @var{sequence} may be modified.
 
 @example
 @group
-(setq x '(a b c))
+(setq x (list 'a 'b 'c))  ; @r{Create a mutable list.}
      @result{} (a b c)
 @end group
 @group
@@ -320,7 +320,7 @@ presented graphically:
   For the vector, it is even simpler because you don't need setq:
 
 @example
-(setq x [1 2 3 4])
+(setq x (copy-sequence [1 2 3 4]))  ; @r{Create a mutable vector.}
      @result{} [1 2 3 4]
 (nreverse x)
      @result{} [4 3 2 1]
@@ -330,7 +330,7 @@ x
 
 Note that unlike @code{reverse}, this function doesn't work with strings.
 Although you can alter string data by using @code{aset}, it is strongly
-encouraged to treat strings as immutable.
+encouraged to treat strings as immutable even when they are mutable.
 
 @end defun
 
@@ -374,11 +374,11 @@ appears in a different position in the list due to the change of
 
 @example
 @group
-(setq nums '(1 3 2 6 5 4 0))
+(setq nums (list 1 3 2 6 5 4 0))  ; @r{Create a mutable list.}
      @result{} (1 3 2 6 5 4 0)
 @end group
 @group
-(sort nums '<)
+(sort nums #'<)
      @result{} (0 1 2 3 4 5 6)
 @end group
 @group
@@ -396,7 +396,7 @@ of @code{sort} and use that.  Most often we store the result back into
 the variable that held the original list:
 
 @example
-(setq nums (sort nums '<))
+(setq nums (sort nums #'<))
 @end example
 
 For the better understanding of what stable sort is, consider the following
@@ -1228,7 +1228,7 @@ This function sets the @var{index}th element of @var{array} to be
 
 @example
 @group
-(setq w [foo bar baz])
+(setq w (vector 'foo 'bar 'baz))  ; @r{Create a mutable vector.}
      @result{} [foo bar baz]
 (aset w 0 'fu)
      @result{} fu
@@ -1237,7 +1237,8 @@ w
 @end group
 
 @group
-(setq x "asdfasfd")
+;; @r{@code{copy-sequence} creates a mutable string.}
+(setq x (copy-sequence "asdfasfd"))
      @result{} "asdfasfd"
 (aset x 3 ?Z)
      @result{} 90
@@ -1246,6 +1247,10 @@ x
 @end group
 @end example
 
+The @var{array} should be mutable; that is, it should not be a constant,
+such as the constants created via quoting or via self-evaluating forms.
+@xref{Constants and Mutability}.
+
 If @var{array} is a string and @var{object} is not a character, a
 @code{wrong-type-argument} error results.  The function converts a
 unibyte string to multibyte if necessary to insert a character.
@@ -1257,7 +1262,8 @@ each element of @var{array} is @var{object}.  It returns @var{array}.
 
 @example
 @group
-(setq a [a b c d e f g])
+;; @r{Create a mutable vector and then fill it with zeros.}
+(setq a (copy-sequence [a b c d e f g]))
      @result{} [a b c d e f g]
 (fillarray a 0)
      @result{} [0 0 0 0 0 0 0]
@@ -1265,7 +1271,8 @@ a
      @result{} [0 0 0 0 0 0 0]
 @end group
 @group
-(setq s "When in the course")
+;; @r{Create a mutable string and then fill it with "-".}
+(setq s (copy-sequence "When in the course"))
      @result{} "When in the course"
 (fillarray s ?-)
      @result{} "------------------"
@@ -1302,7 +1309,9 @@ same way in Lisp input.
   A vector, like a string or a number, is considered a constant for
 evaluation: the result of evaluating it is the same vector.  This does
 not evaluate or even examine the elements of the vector.
-@xref{Self-Evaluating Forms}.
+@xref{Self-Evaluating Forms}.  Vectors written with square brackets
+are constants and should not be modified via @code{aset} or other
+destructive operations.  @xref{Constants and Mutability}.
 
   Here are examples illustrating these principles:
 
@@ -1565,14 +1574,14 @@ For example, here is how to examine the elements of the syntax table:
 @example
 (let (accumulator)
    (map-char-table
-    #'(lambda (key value)
-        (setq accumulator
-              (cons (list
-                     (if (consp key)
-                         (list (car key) (cdr key))
-                       key)
-                     value)
-                    accumulator)))
+    (lambda (key value)
+      (setq accumulator
+            (cons (list
+                   (if (consp key)
+                       (list (car key) (cdr key))
+                     key)
+                   value)
+                  accumulator)))
     (syntax-table))
    accumulator)
 @result{}
diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi
index 14cabc5d79d..a4c9c2549c5 100644
--- a/doc/lispref/strings.texi
+++ b/doc/lispref/strings.texi
@@ -51,10 +51,8 @@ by a distinguished character code.
 operate on them with the general array and sequence functions documented
 in @ref{Sequences Arrays Vectors}.  For example, you can access or
 change individual characters in a string using the functions @code{aref}
-and @code{aset} (@pxref{Array Functions}).  However, note that
-@code{length} should @emph{not} be used for computing the width of a
-string on display; use @code{string-width} (@pxref{Size of Displayed
-Text}) instead.
+and @code{aset} (@pxref{Array Functions}).  However, you should not
+try to change the contents of constant strings (@pxref{Modifying Strings}).
 
   There are two text representations for non-@acronym{ASCII}
 characters in Emacs strings (and in buffers): unibyte and multibyte.
@@ -89,6 +87,9 @@ copy them into buffers.  @xref{Character Type}, and @ref{String Type},
 for information about the syntax of characters and strings.
 @xref{Non-ASCII Characters}, for functions to convert between text
 representations and to encode and decode character codes.
+Also, note that @code{length} should @emph{not} be used for computing
+the width of a string on display; use @code{string-width} (@pxref{Size
+of Displayed Text}) instead.
 
 @node Predicates for Strings
 @section Predicates for Strings
@@ -380,6 +381,11 @@ usual value is @w{@code{"[ \f\t\n\r\v]+"}}.
 @cindex modifying strings
 @cindex string modification
 
+  You can alter the contents of a mutable string via operations
+described in this section.  However, you should not try to use these
+operations to alter the contents of a constant string.
+@xref{Constants and Mutability}.
+
   The most basic way to alter the contents of an existing string is with
 @code{aset} (@pxref{Array Functions}).  @code{(aset @var{string}
 @var{idx} @var{char})} stores @var{char} into @var{string} at index
@@ -591,7 +597,7 @@ for sorting (@pxref{Sequence Functions}):
 
 @example
 @group
-(sort '("11" "12" "1 1" "1 2" "1.1" "1.2") 'string-collate-lessp)
+(sort (list "11" "12" "1 1" "1 2" "1.1" "1.2") 'string-collate-lessp)
      @result{} ("11" "1 1" "1.1" "12" "1 2" "1.2")
 @end group
 @end example
@@ -608,7 +614,7 @@ systems.  The @var{locale} value of @code{"POSIX"} or @code{"C"} lets
 
 @example
 @group
-(sort '("11" "12" "1 1" "1 2" "1.1" "1.2")
+(sort (list "11" "12" "1 1" "1 2" "1.1" "1.2")
       (lambda (s1 s2) (string-collate-lessp s1 s2 "POSIX")))
      @result{} ("1 1" "1 2" "1.1" "1.2" "11" "12")
 @end group
diff --git a/doc/lispref/syntax.texi b/doc/lispref/syntax.texi
index ad45a8edaff..9eb99a0ac92 100644
--- a/doc/lispref/syntax.texi
+++ b/doc/lispref/syntax.texi
@@ -1118,9 +1118,9 @@ bidi-class}).
     ;; 'bidi-class' Unicode property is R, AL, or RLO --
     ;; these have a right-to-left directionality.
     (map-char-table
-     #'(lambda (key val)
-         (if (memq val '(R AL RLO))
-             (modify-category-entry key ?R category-table)))
+     (lambda (key val)
+       (if (memq val '(R AL RLO))
+           (modify-category-entry key ?R category-table)))
      uniprop-table)
     category-table))
 @end example
diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index ffdf952b081..58424a4231b 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -2073,11 +2073,10 @@ its @code{sort-subr} call looks like this:
 @example
 @group
 (sort-subr reverse
-           (function
-            (lambda ()
-              (while (and (not (eobp))
-                          (looking-at paragraph-separate))
-                (forward-line 1))))
+           (lambda ()
+             (while (and (not (eobp))
+                         (looking-at paragraph-separate))
+               (forward-line 1)))
            'forward-paragraph)
 @end group
 @end example
@@ -4679,7 +4678,7 @@ expanded when the header line is computed.  To do this, the
 above.  @var{specification} is an alist that has elements where the
 @code{car} is a character and the @code{cdr} is the substitution.
 
-If @code{ONLY-PRESENT} is @code{nil}, errors will be signalled if a
+If @code{ONLY-PRESENT} is @code{nil}, errors will be signaled if a
 format character has been used that's not present in
 @var{specification}.  If it's non-@code{nil}, that format
 specification is left verbatim in the result.
@@ -5725,7 +5724,7 @@ made within the @code{combine-after-change-calls} body.
 @code{after-change-functions} within
 the body of a @code{combine-after-change-calls} form.
 
-@strong{Warning:} if the changes you combine occur in widely scattered
+@strong{Warning:} If the changes you combine occur in widely scattered
 parts of the buffer, this will still work, but it is not advisable,
 because it may lead to inefficient behavior for some change hook
 functions.
diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index 424e15bc6d1..718e269fc86 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -25668,6 +25668,13 @@ Create non-spam statistics for every file in this directory.  Every
 file is treated as one non-spam mail.
 @end defun
 
+@defvar spam-stat-process-directory-age
+Maximum age of files to be processed, in days.  Without this filter,
+re-training spam-stat with several thousand messages could take a long
+time.  The default is 90, but you might want to set this to a bigger
+value during the initial training.
+@end defvar
+
 Usually you would call @code{spam-stat-process-spam-directory} on a
 directory such as @file{~/Mail/mail/spam} (this usually corresponds to
 the group @samp{nnml:mail.spam}), and you would call
diff --git a/etc/NEWS.27 b/etc/NEWS.27
index 4485bf91650..091c831e9d6 100644
--- a/etc/NEWS.27
+++ b/etc/NEWS.27
@@ -934,7 +934,7 @@ back, customize 'follow-hide-ghost-cursors' to nil.
 *** 'windmove-create-window' when non-nil makes a new window.
 This happens upon moving off the edge of the frame.
 
----
++++
 *** Windmove supports directional window display and selection.
 The new command 'windmove-display-default-keybindings' binds default
 keys with provided modifiers (by default, Shift-Meta) to the commands
@@ -948,7 +948,7 @@ display the buffer in the same window, for example, 'S-M-0 C-h e'
 displays the "*Messages*" buffer in the same window.  'S-M-t C-h C-n'
 displays NEWS in a new tab.
 
----
++++
 *** Windmove also supports directional window deletion.
 The new command 'windmove-delete-default-keybindings' binds default
 keys with provided prefix (by default, 'C-x') and modifiers (by default,
@@ -958,7 +958,7 @@ With a prefix arg 'C-u', also kills the buffer in that window.
 With 'M-0', deletes the selected window and selects the window
 that was in the specified direction.
 
----
++++
 *** New command 'windmove-swap-states-in-direction' binds default keys
 to the commands that swap the states of the selected window with the
 window in the specified direction.
@@ -1011,10 +1011,6 @@ remapped to these, respectively.
 
 ** Dired
 
----
-*** On systems that support suid/guid files, Dired now fontifies the
-permissions of such files with a special face 'dired-set-id'.
-
 +++
 *** New command 'dired-create-empty-file'.
 
@@ -1026,10 +1022,6 @@ It is by default bound to '* N'.
 *** The marking commands now report how many files were marked by the
 command itself, not how many files are marked in total.
 
----
-*** A new face, 'dired-special', is used to highlight sockets, named
-pipes, block devices and character devices.
-
 +++
 *** The new user option 'dired-create-destination-dirs' controls whether
 'dired-do-copy' and 'dired-rename-file' should create non-existent
@@ -1047,6 +1039,14 @@ Dired performs file renaming using underlying version control system.
 *** Zstandard compression is now supported for 'dired-do-compress' and
 'dired-do-compress-to'.
 
+---
+*** On systems that support suid/guid files, Dired now fontifies the
+permissions of such files with a special face 'dired-set-id'.
+
+---
+*** A new face, 'dired-special', is used to highlight sockets, named
+pipes, block devices and character devices.
+
 ** Find-Dired
 
 ---
@@ -1068,12 +1068,6 @@ script.  The default is nil.
 *** New command 'log-edit-generate-changelog-from-diff', bound to 'C-c C-w'.
 This generates ChangeLog entries from the VC fileset diff.
 
----
-*** 'vc-dir' now shows a button allowing you to hide the stash list.
-Controlled by user option 'vc-git-show-stash'.  Default t means show
-the entire list as before.  An integer value limits the list length
-(but still allows you to show the entire list via the button).
-
 +++
 *** Recording ChangeLog entries doesn't require an actual file.
 If a ChangeLog file doesn't exist, and if the new user option
@@ -1084,9 +1078,11 @@ still be used if it exists.)  Set the user option to nil to get the
 previous behavior of always creating a buffer that visits a ChangeLog
 file.
 
----
-*** New user option 'vc-find-revision-no-save'.
-With non-nil, 'vc-find-revision' doesn't write the created buffer to file.
++++
+*** The new 'd' command ('vc-dir-clean-files') in 'vc-dir-mode'
+buffers will delete the marked files (or if no files are marked, the
+file under point).  This command does not notify the VC backend, and
+is mostly useful for unregistered files.
 
 ---
 *** 'vc-dir-ignore' now takes a prefix argument to ignore all marked files.
@@ -1102,6 +1098,12 @@ When some files are marked, only those are stashed.
 When no files are marked, all modified files are stashed, as before.
 
 ---
+*** 'vc-dir' now shows a button allowing you to hide the stash list.
+Controlled by user option 'vc-git-show-stash'.  Default t means show
+the entire list as before.  An integer value limits the list length
+(but still allows you to show the entire list via the button).
+
+---
 *** 'vc-git-stash' is now bound to 'C' in the stash headers.
 
 --
@@ -1133,26 +1135,20 @@ you invoke 'C-x v m' ('vc-merge').
 instead of revision numbers as completion candidates when it prompts
 for a revision.
 
-+++
-*** 'C-u C-x v D' ('vc-root-version-diff') prompts for two revisions
-and compares their entire trees.
-
 ---
 *** New user option 'vc-hg-revert-switches'.
 It specifies switches to pass to Hg's 'revert' command.
 
++++
+*** 'C-u C-x v D' ('vc-root-version-diff') prompts for two revisions
+and compares their entire trees.
+
 ---
 *** 'C-x v M D' ('vc-diff-mergebase') and 'C-x v M L' ('vc-log-mergebase')
 print diffs and logs between the merge base (common ancestor) of two
 given revisions.
 
 +++
-*** The new 'd' command ('vc-dir-clean-files') in 'vc-dir-mode'
-buffers will delete the marked files (or if no files are marked, the
-file under point).  This command does not notify the VC backend, and
-is mostly useful for unregistered files.
-
-+++
 *** New command 'vc-log-search' asks for a pattern, searches it
 in the revision log, and displays matched log entries in the
 log buffer.  For example, 'M-x vc-log-search RET bug#36644 RET'
@@ -1170,6 +1166,10 @@ revision's commit.  (For some less capable VCSes, only the log entry
 is shown.)
 
 ---
+*** New user option 'vc-find-revision-no-save'.
+With non-nil, 'vc-find-revision' doesn't write the created buffer to file.
+
+---
 *** 'C-x v =' can now mimic Magit's diff format.
 Set the new user option 'diff-font-lock-prettify' to t for that, see
 below under "Diff mode".
@@ -3515,6 +3515,10 @@ functions.
 *** 'image-mode' now uses this library to automatically rotate images
 according to the orientation in the Exif data, if any.
 
+*** In 'image-mode' the image is resized automatically to fit in window.
+The image will resize upon first display and whenever the window's
+dimensions change.
+
 ---
 *** New library image-converter.
 If you need to view exotic image formats for which Emacs doesn't have
@@ -3552,6 +3556,8 @@ name to the kill ring.
 With a prefix argument, 'image-rotate' now rotates the image at point
 90 degrees counter-clockwise, instead of the default clockwise.
 
+*** 'image-mode' has a new key prefix 's' for transformation commands.
+
 ** Modules
 
 ---
diff --git a/lib/ieee754.in.h b/lib/ieee754.in.h
index d64bb46e9de..01ca648905f 100644
--- a/lib/ieee754.in.h
+++ b/lib/ieee754.in.h
@@ -67,7 +67,7 @@ union ieee754_float
 #endif                          /* Little endian.  */
       } ieee;
 
-    /* This format makes it easier to see if a NaN is a signalling NaN.  */
+    /* This format makes it easier to see if a NaN is a signaling NaN.  */
     struct
       {
 #if     __BYTE_ORDER == __BIG_ENDIAN
@@ -118,7 +118,7 @@ union ieee754_double
 #endif                          /* Little endian.  */
       } ieee;
 
-    /* This format makes it easier to see if a NaN is a signalling NaN.  */
+    /* This format makes it easier to see if a NaN is a signaling NaN.  */
     struct
       {
 #if     __BYTE_ORDER == __BIG_ENDIAN
diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 4f01918bdb9..13b72196565 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -677,7 +677,7 @@ Each element is (INDEX . VALUE)")
 (byte-defop 112  1 byte-current-buffer)
 (byte-defop 113  0 byte-set-buffer)
 (byte-defop 114  0 byte-save-current-buffer
-  "To make a binding to record the current buffer")
+  "to make a binding to record the current buffer")
 (byte-defop 115  0 byte-set-mark-OBSOLETE)
 (byte-defop 116  1 byte-interactive-p-OBSOLETE)
 
diff --git a/lisp/emacs-lisp/checkdoc.el b/lisp/emacs-lisp/checkdoc.el
index b5581aa3fbb..e4b800786cc 100644
--- a/lisp/emacs-lisp/checkdoc.el
+++ b/lisp/emacs-lisp/checkdoc.el
@@ -2134,7 +2134,7 @@ buffer, otherwise stop after the first error."
     (checkdoc-ispell-init)
     (unless checkdoc-spellcheck-documentation-flag
       ;; this happens when (checkdoc-ispell-init) can't start `ispell-program-name'
-      (user-error "No spellchecker installed: check the variable `ispell-program-name'."))
+      (user-error "No spellchecker installed: check the variable `ispell-program-name'"))
     (save-excursion
       (skip-chars-forward "^a-zA-Z")
       (let (word sym case-fold-search err word-beginning word-end)
diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
index bb10194a946..4408bb58464 100644
--- a/lisp/emacs-lisp/cl-macs.el
+++ b/lisp/emacs-lisp/cl-macs.el
@@ -767,7 +767,7 @@ The result of the body appears to the compiler as a quoted constant."
   "Eval EXPR and choose among clauses on that value.
 Each clause looks like (KEYLIST BODY...).  EXPR is evaluated and
 compared against each key in each KEYLIST; the corresponding BODY
-is evaluated.  If no clause succeeds, cl-case returns nil.  A
+is evaluated.  If no clause succeeds, this macro returns nil.  A
 single non-nil atom may be used in place of a KEYLIST of one
 atom.  A KEYLIST of t or `otherwise' is allowed only in the final
 clause, and matches if no other keys match.  Key values are
@@ -806,10 +806,10 @@ compared by `eql'.
 
 ;;;###autoload
 (defmacro cl-typecase (expr &rest clauses)
-  "Evals EXPR, chooses among clauses on that value.
+  "Eval EXPR and choose among clauses on that value.
 Each clause looks like (TYPE BODY...).  EXPR is evaluated and, if it
 satisfies TYPE, the corresponding BODY is evaluated.  If no clause succeeds,
-cl-typecase returns nil.  A TYPE of t or `otherwise' is allowed only in the
+this macro returns nil.  A TYPE of t or `otherwise' is allowed only in the
 final clause, and matches if no other keys match.
 \n(fn EXPR (TYPE BODY...)...)"
   (declare (indent 1)
@@ -2701,7 +2701,7 @@ pairs for that slot.
 Supported keywords for slots are:
 - `:read-only':  If this has a non-nil value, that slot cannot be set via `setf'.
 - `:documentation': this is a docstring describing the slot.
-- `:type': the type of the field; currently unused.
+- `:type': the type of the field; currently only used for documentation.
 
 \(fn NAME &optional DOCSTRING &rest SLOTS)"
   (declare (doc-string 2) (indent 1)
diff --git a/lisp/emacs-lisp/elp.el b/lisp/emacs-lisp/elp.el
index 7dd3cbd1a21..f68c0faf09d 100644
--- a/lisp/emacs-lisp/elp.el
+++ b/lisp/emacs-lisp/elp.el
@@ -238,7 +238,7 @@ FUNSYM must be a symbol of a defined function."
     ;; The info vector data structure is a 2 element vector.  The 0th
     ;; element is the call-count, i.e. the total number of times this
     ;; function has been entered.  This value is bumped up on entry to
-    ;; the function so that non-local exists are still recorded. TBD:
+    ;; the function so that non-local exits are still recorded. TBD:
     ;; I haven't tested non-local exits at all, so no guarantees.
     ;;
     ;; The 1st element is the total amount of time in seconds that has
diff --git a/lisp/emacs-lisp/generator.el b/lisp/emacs-lisp/generator.el
index 27ed29925b3..ba344eb5150 100644
--- a/lisp/emacs-lisp/generator.el
+++ b/lisp/emacs-lisp/generator.el
@@ -59,7 +59,7 @@
 ;; This raw form of iteration is general, but a bit awkward to use, so
 ;; this library also provides some convenience functions:
 ;;
-;; `iter-do' is like `cl-do', except that instead of walking a list,
+;; `iter-do' is like `dolist', except that instead of walking a list,
 ;; it walks an iterator.  `cl-loop' is also extended with a new
 ;; keyword, `iter-by', that iterates over an iterator.
 ;;
@@ -67,7 +67,7 @@
 ;;; Implementation:
 
 ;;
-;; The internal cps transformation code uses the cps- namespace.
+;; The internal CPS transformation code uses the cps- namespace.
 ;; Iteration functions use the `iter-' namespace.  Generator functions
 ;; are somewhat less efficient than conventional elisp routines,
 ;; although we try to avoid CPS transformation on forms that do not
@@ -89,13 +89,13 @@
   `(gensym (format ,fmt ,@args)))
 
 (defvar cps--dynamic-wrappers '(identity)
-  "List of transformer functions to apply to atomic forms we
-evaluate in CPS context.")
+  "List of functions to apply to atomic forms.
+These are transformer functions applied to atomic forms evaluated
+in CPS context.")
 
 (defconst cps-standard-special-forms
   '(setq setq-default throw interactive)
-  "List of special forms that we treat just like ordinary
-  function applications." )
+  "List of special forms treated just like ordinary function applications." )
 
 (defun cps--trace-funcall (func &rest args)
   (message "%S: args=%S" func args)
@@ -118,17 +118,15 @@ evaluate in CPS context.")
        (error "%s not supported in generators" ,function)))
 
 (defmacro cps--with-value-wrapper (wrapper &rest body)
-  "Continue generating CPS code with an atomic-form wrapper
-to the current stack of such wrappers.  WRAPPER is a function that
-takes a form and returns a wrapped form.
+  "Evaluate BODY with WRAPPER added to the stack of atomic-form wrappers.
+WRAPPER is a function that takes an atomic form and returns a wrapped form.
 
 Whenever we generate an atomic form (i.e., a form that can't
 `iter-yield'), we first (before actually inserting that form in our
 generated code) pass that form through all the transformer
 functions.  We use this facility to wrap forms that can transfer
 control flow non-locally in goo that diverts this control flow to
-the CPS state machinery.
-"
+the CPS state machinery."
   (declare (indent 1))
   `(let ((cps--dynamic-wrappers
           (cons
@@ -153,7 +151,7 @@ DYNAMIC-VAR bound to STATIC-VAR."
      ,@body))
 
 (defun cps--add-state (kind body)
-  "Create a new CPS state with body BODY and return the state's name."
+  "Create a new CPS state of KIND with BODY and return the state's name."
   (declare (indent 1))
   (let ((state (cps--gensym "cps-state-%s-" kind)))
     (push (list state body cps--cleanup-function) cps--states)
@@ -170,14 +168,12 @@ DYNAMIC-VAR bound to STATIC-VAR."
     (and (fboundp handler) handler)))
 
 (defvar cps-inhibit-atomic-optimization nil
-  "When non-nil, always rewrite forms into cps even when they
-don't yield.")
+  "When non-nil, always rewrite forms into CPS even when they don't yield.")
 
 (defvar cps--yield-seen)
 
 (defun cps--atomic-p (form)
-  "Return whether the given form never yields."
-
+  "Return nil if FORM can yield, non-nil otherwise."
   (and (not cps-inhibit-atomic-optimization)
        (let* ((cps--yield-seen))
          (ignore (macroexpand-all
@@ -649,8 +645,8 @@ modified copy."
 (defun iter-yield (value)
   "When used inside a generator, yield control to caller.
 The caller of `iter-next' receives VALUE, and the next call to
-`iter-next' resumes execution at the previous
-`iter-yield' point."
+`iter-next' resumes execution with the form immediately following this
+`iter-yield' call."
   (identity value)
   (error "`iter-yield' used outside a generator"))
 
diff --git a/lisp/emacs-lisp/gv.el b/lisp/emacs-lisp/gv.el
index 3ab49293e90..096036a0ffa 100644
--- a/lisp/emacs-lisp/gv.el
+++ b/lisp/emacs-lisp/gv.el
@@ -38,7 +38,7 @@
 ;;
 ;; Instead, we use here a higher-order approach: instead
 ;; of a 5-tuple, a place-expander returns a function.
-;; If you think about types, the old approach return things of type
+;; If you think about types, the old approach returns things of type
 ;;    {vars: List Var, values: List Exp,
 ;;     stores: List Var, getter: Exp, setter: Exp}
 ;; whereas the new approach returns a function of type
diff --git a/lisp/emacs-lisp/lisp-mode.el b/lisp/emacs-lisp/lisp-mode.el
index 3b0f5493eeb..98c44161ad0 100644
--- a/lisp/emacs-lisp/lisp-mode.el
+++ b/lisp/emacs-lisp/lisp-mode.el
@@ -535,7 +535,7 @@ This will generate compile-time constants from BINDINGS."
 
 ;; Support backtrace mode.
 (defconst lisp-el-font-lock-keywords-for-backtraces lisp-el-font-lock-keywords
-  "Default highlighting from Emacs Lisp mod used in Backtrace mode.")
+  "Default highlighting from Emacs Lisp mode used in Backtrace mode.")
 (defconst lisp-el-font-lock-keywords-for-backtraces-1 lisp-el-font-lock-keywords-1
   "Subdued highlighting from Emacs Lisp mode used in Backtrace mode.")
 (defconst lisp-el-font-lock-keywords-for-backtraces-2
diff --git a/lisp/image-mode.el b/lisp/image-mode.el
index 22d7d913141..fbce1193cd0 100644
--- a/lisp/image-mode.el
+++ b/lisp/image-mode.el
@@ -418,24 +418,40 @@ call."
 
 (defvar image-mode-map
   (let ((map (make-sparse-keymap)))
+
+    ;; Toggling keys
     (define-key map "\C-c\C-c" 'image-toggle-display)
     (define-key map "\C-c\C-x" 'image-toggle-hex-display)
-    (define-key map (kbd "SPC")       'image-scroll-up)
-    (define-key map (kbd "S-SPC")     'image-scroll-down)
-    (define-key map (kbd "DEL")       'image-scroll-down)
-    (define-key map (kbd "RET")       'image-toggle-animation)
+
+    ;; Transformation keys
+    (define-key map "sf" 'image-mode-fit-frame)
+    (define-key map "sh" 'image-transform-fit-to-height)
+    (define-key map "sw" 'image-transform-fit-to-width)
+    (define-key map "sr" 'image-transform-set-rotation)
+    (define-key map "s0" 'image-transform-reset)
+    (define-key map "ss" 'image-transform-set-scale)
+
+    ;; Multi-frame keys
+    (define-key map (kbd "RET") 'image-toggle-animation)
     (define-key map "F" 'image-goto-frame)
     (define-key map "f" 'image-next-frame)
     (define-key map "b" 'image-previous-frame)
-    (define-key map "n" 'image-next-file)
-    (define-key map "p" 'image-previous-file)
     (define-key map "a+" 'image-increase-speed)
     (define-key map "a-" 'image-decrease-speed)
     (define-key map "a0" 'image-reset-speed)
     (define-key map "ar" 'image-reverse-speed)
+
+    ;; File keys
+    (define-key map "n" 'image-next-file)
+    (define-key map "p" 'image-previous-file)
     (define-key map "w" 'image-mode-copy-file-name-as-kill)
     (define-key map "m" 'image-mode-mark-file)
     (define-key map "u" 'image-mode-unmark-file)
+
+    ;; Scrolling keys
+    (define-key map (kbd "SPC")   'image-scroll-up)
+    (define-key map (kbd "S-SPC") 'image-scroll-down)
+    (define-key map (kbd "DEL")   'image-scroll-down)
     (define-key map [remap forward-char] 'image-forward-hscroll)
     (define-key map [remap backward-char] 'image-backward-hscroll)
     (define-key map [remap right-char] 'image-forward-hscroll)
@@ -452,6 +468,7 @@ call."
     (define-key map [remap move-end-of-line] 'image-eol)
     (define-key map [remap beginning-of-buffer] 'image-bob)
     (define-key map [remap end-of-buffer] 'image-eob)
+
     (easy-menu-define image-mode-menu map "Menu for Image mode."
       '("Image"
         ["Show as Text" image-toggle-display :active t
@@ -459,17 +476,15 @@ call."
     ["Show as Hex" image-toggle-hex-display :active t
      :help "Show image as hex"]
         "--"
+        ["Fit Frame to Image" image-mode-fit-frame :active t
+         :help "Resize frame to match image"]
         ["Fit to Window Height" image-transform-fit-to-height
-         :visible (eq image-type 'imagemagick)
          :help "Resize image to match the window height"]
         ["Fit to Window Width" image-transform-fit-to-width
-         :visible (eq image-type 'imagemagick)
          :help "Resize image to match the window width"]
         ["Rotate Image..." image-transform-set-rotation
-         :visible (eq image-type 'imagemagick)
          :help "Rotate the image"]
         ["Reset Transformations" image-transform-reset
-         :visible (eq image-type 'imagemagick)
          :help "Reset all image transformations"]
         "--"
         ["Show Thumbnails"
@@ -486,9 +501,6 @@ call."
          :active buffer-file-name
          :help "Copy the current file name to the kill ring"]
         "--"
-        ["Fit Frame to Image" image-mode-fit-frame :active t
-         :help "Resize frame to match image"]
-        "--"
         ["Animate Image" image-toggle-animation :style toggle
          :selected (let ((image (image-get-display-property)))
                      (and image (image-animate-timer image)))
@@ -767,11 +779,12 @@ was inserted."
          props image)
 
     ;; Get the rotation data from the file, if any.
-    (setq image-transform-rotation
-          (or (exif-orientation
-               (ignore-error exif-error
-                 (exif-parse-buffer)))
-              0.0))
+    (when (zerop image-transform-rotation) ; don't reset modified value
+      (setq image-transform-rotation
+            (or (exif-orientation
+                 (ignore-error exif-error
+                   (exif-parse-buffer)))
+                0.0)))
 
     ;; :scale 1: If we do not set this, create-image will apply
     ;; default scaling based on font size.
@@ -1250,8 +1263,7 @@ Do this for an image of type `imagemagick' to make sure that the
 elisp code matches the way ImageMagick computes the bounding box
 of a rotated image."
   (when (and (not (numberp image-transform-resize))
-             (boundp 'image-type)
-             (eq image-type 'imagemagick))
+             (boundp 'image-type))
     (let ((size (image-display-size (image-get-display-property) t)))
       (cond ((eq image-transform-resize 'fit-width)
              (cl-assert (= (car size)
@@ -1268,10 +1280,7 @@ of a rotated image."
   "Return rescaling/rotation properties for image SPEC.
 These properties are determined by the Image mode variables
 `image-transform-resize' and `image-transform-rotation'.  The
-return value is suitable for appending to an image spec.
-
-Rescaling and rotation properties only take effect if Emacs is
-compiled with ImageMagick support."
+return value is suitable for appending to an image spec."
   (setq image-transform-scale 1.0)
   (when (or image-transform-resize
             (/= image-transform-rotation 0.0))
@@ -1302,41 +1311,32 @@ compiled with ImageMagick support."
             (list :rotation image-transform-rotation))))))
 
 (defun image-transform-set-scale (scale)
-  "Prompt for a number, and resize the current image by that amount.
-This command has no effect unless Emacs is compiled with
-ImageMagick support."
+  "Prompt for a number, and resize the current image by that amount."
   (interactive "nScale: ")
   (setq image-transform-resize scale)
   (image-toggle-display-image))
 
 (defun image-transform-fit-to-height ()
-  "Fit the current image to the height of the current window.
-This command has no effect unless Emacs is compiled with
-ImageMagick support."
+  "Fit the current image to the height of the current window."
   (interactive)
   (setq image-transform-resize 'fit-height)
   (image-toggle-display-image))
 
 (defun image-transform-fit-to-width ()
-  "Fit the current image to the width of the current window.
-This command has no effect unless Emacs is compiled with
-ImageMagick support."
+  "Fit the current image to the width of the current window."
   (interactive)
   (setq image-transform-resize 'fit-width)
   (image-toggle-display-image))
 
 (defun image-transform-set-rotation (rotation)
   "Prompt for an angle ROTATION, and rotate the image by that amount.
-ROTATION should be in degrees.  This command has no effect unless
-Emacs is compiled with ImageMagick support."
+ROTATION should be in degrees."
   (interactive "nRotation angle (in degrees): ")
   (setq image-transform-rotation (float (mod rotation 360)))
   (image-toggle-display-image))
 
 (defun image-transform-reset ()
-  "Display the current image with the default size and rotation.
-This command has no effect unless Emacs is compiled with
-ImageMagick support."
+  "Display the current image with the default size and rotation."
   (interactive)
   (setq image-transform-resize nil
         image-transform-rotation 0.0
diff --git a/lisp/image/exif.el b/lisp/image/exif.el
index 065456dc318..6aeb52c726d 100644
--- a/lisp/image/exif.el
+++ b/lisp/image/exif.el
@@ -95,7 +95,7 @@ mirrored or not.")
   "Parse FILE (a JPEG file) and return the Exif data, if any.
 The return value is a list of Exif items.
 
-If the data is invalid, an `exif-error' is signalled."
+If the data is invalid, an `exif-error' is signaled."
   (with-temp-buffer
     (set-buffer-multibyte nil)
     (insert-file-contents-literally file)
@@ -105,7 +105,7 @@ If the data is invalid, an `exif-error' is signalled."
   "Parse BUFFER (which should be a JPEG file) and return the Exif data, if any.
 The return value is a list of Exif items.
 
-If the data is invalid, an `exif-error' is signalled."
+If the data is invalid, an `exif-error' is signaled."
   (setq buffer (or buffer (current-buffer)))
   (with-current-buffer buffer
     (if enable-multibyte-characters
diff --git a/lisp/international/mule-util.el b/lisp/international/mule-util.el
index caa5747817c..5cc10b1315a 100644
--- a/lisp/international/mule-util.el
+++ b/lisp/international/mule-util.el
@@ -75,7 +75,7 @@ unless the display width of STR is equal to or less than the display
 width of ELLIPSIS.  If it is non-nil and not a string, then ELLIPSIS
 defaults to `truncate-string-ellipsis'.
 
-If ELLIPSIS-TEXT-PROPERTY in non-nil, a too-long string will not
+If ELLIPSIS-TEXT-PROPERTY is non-nil, a too-long string will not
 be truncated, but instead the elided parts will be covered by a
 `display' text property showing the ellipsis."
   (or start-column
diff --git a/lisp/json.el b/lisp/json.el
index 055f3f5be11..6f3b791ed17 100644
--- a/lisp/json.el
+++ b/lisp/json.el
@@ -736,7 +736,7 @@ you will get the following structure returned:
 
 OBJECT should have a structure like one returned by `json-read'.
 If an error is detected during encoding, an error based on
-`json-error' is signalled."
+`json-error' is signaled."
   (cond ((memq object (list t json-null json-false))
          (json-encode-keyword object))
         ((stringp object)      (json-encode-string object))
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index 6090e3f74ed..d2c3f9045e5 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -163,8 +163,8 @@ perform completion, no matter what ACTION is.
 
 If ACTION is `metadata' or a list where the first element is
 `boundaries', return nil.  If ACTION is nil, this function works
-like `try-completion'; if it's t, this function works like
-`all-completion'; and any other values makes it work like
+like `try-completion'; if it is t, this function works like
+`all-completion'; and any other value makes it work like
 `test-completion'."
   (cond
    ((functionp collection) (funcall collection string predicate action))
diff --git a/lisp/obsolete/cl.el b/lisp/obsolete/cl.el
index 1da4289b695..20bffffd781 100644
--- a/lisp/obsolete/cl.el
+++ b/lisp/obsolete/cl.el
@@ -509,7 +509,7 @@ This method shows how to handle `setf's to places of the form
 ARGLIST, as if NAME were going to be expanded as a macro, then
 the BODY forms are executed and must return a list of five elements:
 a temporary-variables list, a value-forms list, a store-variables list
-\(of length one), a store-form, and an access- form.
+\(of length one), a store-form, and an access-form.
 
 See `gv-define-expander', and `gv-define-setter' for better and
 simpler ways to define setf-methods."
diff --git a/lisp/sort.el b/lisp/sort.el
index e4ff2afb3d7..de0e1b9519d 100644
--- a/lisp/sort.el
+++ b/lisp/sort.el
@@ -198,7 +198,8 @@ as start and end positions), and with `string<' otherwise."
 
 ;;;###autoload
 (defun sort-lines (reverse beg end)
-  "Sort lines in region alphabetically; argument means descending order.
+  "Sort lines in region alphabetically; REVERSE non-nil means descending order.
+Interactively, REVERSE is the prefix argument, and BEG and END are the region.
 Called from a program, there are three arguments:
 REVERSE (non-nil means reverse order), BEG and END (region to sort).
 The variable `sort-fold-case' determines whether alphabetic case affects
diff --git a/lisp/startup.el b/lisp/startup.el
index 5af264e3ef7..bff10003f84 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -352,11 +352,11 @@ Setting `init-file-user' does not prevent Emacs from loading
 
 (defcustom site-run-file (purecopy "site-start")
   "File containing site-wide run-time initializations.
-This file is loaded at run-time before `~/.emacs'.  It contains inits
-that need to be in place for the entire site, but which, due to their
-higher incidence of change, don't make sense to put into Emacs's
+This file is loaded at run-time before `user-init-file'.  It contains
+inits that need to be in place for the entire site, but which, due to
+their higher incidence of change, don't make sense to put into Emacs's
 dump file.  Thus, the run-time load order is: 1. file described in
-this variable, if non-nil; 2. `~/.emacs'; 3. `default.el'.
+this variable, if non-nil; 2. `user-init-file'; 3. `default.el'.
 
 Don't use the `site-start.el' file for things some users may not like.
 Put them in `default.el' instead, so that users can more easily
diff --git a/lisp/subr.el b/lisp/subr.el
index f7445d8c25e..c8913145a18 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -385,7 +385,7 @@ entry to the debugger, even when `debug-on-error' is non-nil.
 This can be overridden by `debug-ignored-errors'.
 
 To signal with MESSAGE without interpreting format characters
-like `%', `\\=`' and `\\='', use (error \"%s\" MESSAGE).
+like `%', `\\=`' and `\\='', use (user-error \"%s\" MESSAGE).
 In Emacs, the convention is that error messages start with a capital
 letter but *do not* end with a period.  Please follow this convention
 for the sake of consistency."
@@ -3314,7 +3314,7 @@ alternatives."
 
 (defun function-get (f prop &optional autoload)
   "Return the value of property PROP of function F.
-If AUTOLOAD is non-nil and F is autoloaded, try to autoload it
+If AUTOLOAD is non-nil and F is autoloaded, try to load it
 in the hope that it will set PROP.  If AUTOLOAD is `macro', do it only
 if it's an autoloaded macro."
   (let ((val nil))
@@ -5021,7 +5021,7 @@ The properties used on SYMBOL are `composefunc', `sendfunc',
 (defun backtrace-frames (&optional base)
   "Collect all frames of current backtrace into a list.
 If non-nil, BASE should be a function, and frames before its
-nearest activation frames are discarded."
+nearest activation frame are discarded."
   (let ((frames nil))
     (mapbacktrace (lambda (&rest frame) (push frame frames))
                   (or base 'backtrace-frames))
diff --git a/lisp/textmodes/ispell.el b/lisp/textmodes/ispell.el
index a9fbd2f04cb..65f61644b6d 100644
--- a/lisp/textmodes/ispell.el
+++ b/lisp/textmodes/ispell.el
@@ -800,8 +800,8 @@ Otherwise returns the library directory name, if that is defined."
 
 (defun ispell-create-debug-buffer (&optional append)
   "Create an ispell debug buffer for debugging output.
-If APPEND is non-nil, append the info to previous buffer if exists,
-otherwise is reset.  Returns name of ispell debug buffer.
+If APPEND is non-nil, add output to the old buffer if it exists,
+otherwise the buffer is erased first.  Returns the debug buffer.
 See `ispell-buffer-with-debug' for an example of use."
   (let ((ispell-debug-buffer (get-buffer-create "*ispell-debug*")))
     (with-current-buffer ispell-debug-buffer
@@ -812,7 +812,7 @@ See `ispell-buffer-with-debug' for an example of use."
     ispell-debug-buffer))
 
 (defsubst ispell-print-if-debug (format &rest args)
-  "Print message using FORMAT and ARGS to `ispell-debug-buffer' buffer if enabled."
+  "Print message using FORMAT and ARGS to `ispell-debug-buffer' if enabled."
   (if (boundp 'ispell-debug-buffer)
       (with-current-buffer ispell-debug-buffer
         (goto-char (point-max))
@@ -3618,8 +3618,8 @@ Returns the sum SHIFT due to changes in word replacements."
 
 ;;;###autoload
 (defun ispell-buffer-with-debug (&optional append)
-  "`ispell-buffer' with some output sent to `ispell-debug-buffer' buffer.
-If APPEND is non-n il, append the info to previous buffer if exists."
+  "`ispell-buffer' with some output sent to `ispell-debug-buffer'.
+If APPEND is non-nil, don't erase previous debugging output."
   (interactive)
   (let ((ispell-debug-buffer (ispell-create-debug-buffer append)))
     (ispell-buffer)))
diff --git a/src/eval.c b/src/eval.c
index 78a787c4ffd..014905ce6df 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1229,7 +1229,7 @@ The car of a handler may be a list of condition names instead of a
 single condition name; then it handles all of them.  If the special
 condition name `debug' is present in this list, it allows another
 condition in the list to run the debugger if `debug-on-error' and the
-other usual mechanisms says it should (otherwise, `condition-case'
+other usual mechanisms say it should (otherwise, `condition-case'
 suppresses the debugger).
 
 When a handler handles an error, control returns to the `condition-case'
diff --git a/src/lread.c b/src/lread.c
index c6607a8935f..59bf529f45c 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -4881,7 +4881,7 @@ features required.  Each entry has the form `(provide . FEATURE)',
 `(defface . SYMBOL)', `(define-type . SYMBOL)',
 `(cl-defmethod METHOD SPECIALIZERS)', or `(t . SYMBOL)'.
 Entries like `(t . SYMBOL)' may precede a `(defun . FUNCTION)' entry,
-and means that SYMBOL was an autoload before this file redefined it
+and mean that SYMBOL was an autoload before this file redefined it
 as a function.  In addition, entries may also be single symbols,
 which means that symbol was defined by `defvar' or `defconst'.
 
diff --git a/src/regex-emacs.c b/src/regex-emacs.c
index 9cade11c9fb..ba7f3cef64b 100644
--- a/src/regex-emacs.c
+++ b/src/regex-emacs.c
@@ -3954,9 +3954,11 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
 
   /* Prevent shrinking and relocation of buffer text if GC happens
      while we are inside this function.  The calls to
-     UPDATE_SYNTAX_TABLE_* macros can trigger GC if they call Lisp,
-     and we have C pointers to buffer text that must not become
-     invalid as result of GC.  */
+     UPDATE_SYNTAX_TABLE_* macros can call Lisp (via
+     `internal--syntax-propertize`); these calls are careful to defend against
+     buffer modifications, but even with no modifications, the buffer text may
+     be relocated during GC by `compact_buffer` which would invalidate
+     our C pointers to buffer text.  */
   if (!current_buffer->text->inhibit_shrinking)
     {
       record_unwind_protect_ptr (unwind_re_match, current_buffer);
diff --git a/src/syntax.c b/src/syntax.c
index c765cc9a17b..a03202d386c 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -480,10 +480,10 @@ parse_sexp_propertize (ptrdiff_t charpos)
       safe_call1 (Qinternal__syntax_propertize,
                   make_fixnum (min (zv, 1 + charpos)));
       if (modiffs != CHARS_MODIFF)
-        error ("parse-sexp-propertize-function modified the buffer!");
+        error ("internal--syntax-propertize modified the buffer!");
       if (syntax_propertize__done <= charpos
           && syntax_propertize__done < zv)
-        error ("parse-sexp-propertize-function did not move"
+        error ("internal--syntax-propertize did not move"
                " syntax-propertize--done");
       SETUP_SYNTAX_TABLE (charpos, 1);
     }
diff --git a/test/lisp/jsonrpc-tests.el b/test/lisp/jsonrpc-tests.el
index 63c4c32d45f..6c08023d4f3 100644
--- a/test/lisp/jsonrpc-tests.el
+++ b/test/lisp/jsonrpc-tests.el
@@ -114,7 +114,7 @@
     (condition-case err
         (progn
           (jsonrpc-request conn 'delete-directory "~/tmp")
-          (ert-fail "A `jsonrpc-error' should have been signalled!"))
+          (ert-fail "A `jsonrpc-error' should have been signaled!"))
       (jsonrpc-error
        (should (= -32601 (cdr (assoc 'jsonrpc-error-code (cdr err)))))))))
 
@@ -124,7 +124,7 @@
     (condition-case err
         (progn
           (jsonrpc-request conn '+ ["a" 2])
-          (ert-fail "A `jsonrpc-error' should have been signalled!"))
+          (ert-fail "A `jsonrpc-error' should have been signaled!"))
       (jsonrpc-error
        (should (= -32603 (cdr (assoc 'jsonrpc-error-code (cdr err)))))))))
 
diff --git a/test/src/thread-tests.el b/test/src/thread-tests.el
index 6673ac4b4eb..5d85fc74e50 100644
--- a/test/src/thread-tests.el
+++ b/test/src/thread-tests.el
@@ -112,7 +112,7 @@
   (should-error (thread-join (current-thread))))
 
 (ert-deftest threads-join-error ()
-  "Test of error signalling from `thread-join'."
+  "Test of error signaling from `thread-join'."
   :tags '(:unstable)
   (skip-unless (featurep 'threads))
   (let ((thread (make-thread #'threads-call-error)))