Prefer ASCII in doc and comments when the difference does not matter.

doc/emacs/maintaining.texi

@@ -1046,7 +1046,7 @@ Ignore a file under current version control system.  (@code{vc-ignore}).
 @findex vc-ignore
   Many source trees contain some files that do not need to be
 versioned, such as editor backups, object or bytecode files, and built
-programs.  You can simply not add them, but then they’ll always crop
+programs.  You can simply not add them, but then they'll always crop
 up as unknown files.  You can also tell the version control system to
 ignore these files by adding them to the ignore file at the top of the
 tree.  @kbd{C-x v G} (@code{vc-ignore}) can help you do this.  When

doc/emacs/text.texi

@@ -2086,7 +2086,7 @@ newlines are used for filling.  The @key{RET} (@code{newline}) and
 commands, including Auto Fill (@pxref{Auto Fill}), insert only soft
 newlines and delete only soft newlines, leaving hard newlines alone.
 
-@c FIXME: I don't see ‘unfilled’ in that node.  --xfq
+@c FIXME: I don't see 'unfilled' in that node.  --xfq
   Thus, when editing with Enriched mode, you should not use @key{RET}
 or @kbd{C-o} to break lines in the middle of filled paragraphs.  Use
 Auto Fill mode or explicit fill commands (@pxref{Fill Commands})

doc/lispref/display.texi

@@ -615,8 +615,8 @@ program signals a Lisp error and then handles it with
 @code{condition-case}, the user won't see the error message; it could
 show the message to the user by reporting it as a warning.)
 
-@c FIXME: Why use ‘(bytecomp)’ instead of ‘'bytecomp’ or simply
-@c ‘bytecomp’ here?  The parens are part of ‘warning-type-format’ but
+@c FIXME: Why use "(bytecomp)" instead of "'bytecomp" or simply
+@c "bytecomp" here?  The parens are part of warning-type-format but
 @c not part of the warning type. --xfq
 @cindex warning type
   Each warning has a @dfn{warning type} to classify it.  The type is a
@@ -2044,7 +2044,7 @@ stipple patterns.
 Alternative foreground color, a string.  This is like @code{:foreground}
 but the color is only used as a foreground when the background color is
 near to the foreground that would have been used.  This is useful for
-example when marking text (i.e. the region face).  If the text has a foreground 
+example when marking text (i.e. the region face).  If the text has a foreground
 that is visible with the region face, that foreground is used.
 If the foreground is near the region face background,
 @code{:distant-foreground} is used instead so the text is readable.
@@ -3589,8 +3589,8 @@ See the next subsection for details.
 @xref{Fringe Bitmaps}.
 @end ifnottex
 
-@c FIXME: I can't find the ‘fringes-indicator-alist’ variable.  Maybe
-@c it should be ‘fringe-indicator-alist’ or ‘fringe-cursor-alist’?  --xfq
+@c FIXME: I can't find the fringes-indicator-alist variable.  Maybe
+@c it should be fringe-indicator-alist or fringe-cursor-alist?  --xfq
 When @code{fringe-cursor-alist} has a buffer-local value, and there is
 no bitmap defined for a cursor type, the corresponding value from the
 default value of @code{fringes-indicator-alist} is used.
@@ -4712,7 +4712,7 @@ and if @code{:height} is set it will have precedence over
 wish.  @code{:max-width} and @code{:max-height} will always preserve
 the aspect ratio.
 
-@c FIXME: ‘:format-type’ or ‘:format’?  --xfq
+@c FIXME: ':format-type' or ':format'?  --xfq
 @item :format
 ImageMagick tries to auto-detect the image type, but it isn't always
 able to.  By using @code{:format-type}, we can give ImageMagick a hint
@@ -4793,7 +4793,7 @@ from the file's name.
 The remaining arguments, @var{props}, specify additional image
 properties---for example,
 
-@c ‘:heuristic-mask’ is not documented?
+@c ':heuristic-mask' is not documented?
 @example
 (create-image "foo.xpm" 'xpm nil :heuristic-mask t)
 @end example

doc/lispref/nonascii.texi

@@ -550,15 +550,13 @@ is @code{nil}, which means the character itself.
 @defun get-char-code-property char propname
 This function returns the value of @var{char}'s @var{propname} property.
 
-@c FIXME: Use ‘?\s’ instead of ‘? ’ for the space character in the
-@c first example?  --xfq
 @example
 @group
-(get-char-code-property ?  'general-category)
+(get-char-code-property ?\s 'general-category)
      @result{} Zs
 @end group
 @group
-(get-char-code-property ?1  'general-category)
+(get-char-code-property ?1 'general-category)
      @result{} Nd
 @end group
 @group
@@ -688,7 +686,7 @@ which case the returned charset must be supported by that coding
 system (@pxref{Coding Systems}).
 @end defun
 
-@c TODO: Explain the properties here and add indexes such as ‘charset property’.
+@c TODO: Explain the properties here and add indexes such as 'charset property'.
 @defun charset-plist charset
 This function returns the property list of the character set
 @var{charset}.  Although @var{charset} is a symbol, this is not the

doc/misc/ido.texi

@@ -576,7 +576,7 @@ enable it:
 
 Now you can customize @code{completion-ignored-extensions} as well.
 Go ahead and add all the useless object files, backup files, shared
-library files and other computing flotsam you don’t want Ido to show.
+library files and other computing flotsam you don't want Ido to show.
 
 @strong{Please notice:} Ido will still complete the ignored elements
 if it would otherwise not show any other matches.  So if you type out

doc/misc/org.texi

@@ -13071,7 +13071,7 @@ channel."
 @end lisp
 
 The @code{my-ascii-src-block} function looks at the attribute above the
-element.  If it isn’t true, it gives hand to the @code{ascii} back-end.
+element.  If it isn't true, it gives hand to the @code{ascii} back-end.
 Otherwise, it creates a box around the code, leaving room for the language.
 A new back-end is then created.  It only changes its behaviour when
 translating @code{src-block} type element.  Now, all it takes to use the new
@@ -13778,7 +13778,7 @@ ensure that no code blocks are evaluated as part of the export process.  This
 can be useful in situations where potentially untrusted Org mode files are
 exported in an automated fashion, for example when Org mode is used as the
 markup language for a wiki.  It is also possible to set this variable to
-@code{‘inline-only}.  In that case, only inline code blocks will be
+@code{'inline-only}.  In that case, only inline code blocks will be
 evaluated, in order to insert their results.  Non-inline code blocks are
 assumed to have their results already inserted in the buffer by manual
 evaluation.  This setting is useful to avoid expensive recalculations during

src/lread.c

@@ -2053,7 +2053,7 @@ STREAM or the value of `standard-input' may be:
   if (EQ (stream, Qt))
     stream = Qread_char;
   if (EQ (stream, Qread_char))
-    /* FIXME: ¿¡ When is this used !?  */
+    /* FIXME: ?! When is this used !?  */
     return call1 (intern ("read-minibuffer"),
 		  build_string ("Lisp expression: "));