Replace `iff' in doc-strings and comments.

40 files changed, 108 insertions, 94 deletions

diff --git a/lisp/abbrev.el b/lisp/abbrev.el
index 1471ca7bebd..b2b03fe63bb 100644
--- a/lisp/abbrev.el
+++ b/lisp/abbrev.el
@@ -39,9 +39,9 @@ define global abbrevs instead."
 
 (defun abbrev-mode (&optional arg)
   "Toggle Abbrev mode in the current buffer.
-With argument ARG, turn abbrev mode on iff ARG is positive.
-In Abbrev mode, inserting an abbreviation causes it to expand
-and be replaced by its expansion."
+With optional argument ARG, turn abbrev mode on if ARG is
+positive, otherwise turn it off.  In Abbrev mode, inserting an
+abbreviation causes it to expand and be replaced by its expansion."
   (interactive "P")
   (setq abbrev-mode
 	(if (null arg) (not abbrev-mode)
diff --git a/lisp/allout.el b/lisp/allout.el
index f6598063e97..d243a188812 100644
--- a/lisp/allout.el
+++ b/lisp/allout.el
@@ -1658,8 +1658,9 @@ the following two lines in your Emacs init file:
   "Toggle minor mode for controlling exposure and editing of text outlines.
 \\<allout-mode-map>
 
-Optional arg forces mode to re-initialize iff arg is positive num or
-symbol.  Allout outline mode always runs as a minor mode.
+Optional prefix argument TOGGLE forces the mode to re-initialize
+if it is positive, otherwise it turns the mode off.  Allout
+outline mode always runs as a minor mode.
 
 Allout outline mode provides extensive outline oriented formatting and
 manipulation.  It enables structural editing of outlines, as well as
diff --git a/lisp/autorevert.el b/lisp/autorevert.el
index cad94e789d6..5220f3f6dea 100644
--- a/lisp/autorevert.el
+++ b/lisp/autorevert.el
@@ -315,7 +315,7 @@ This function is designed to be added to hooks, for example:
 ;;;###autoload
 (define-minor-mode auto-revert-tail-mode
   "Toggle reverting tail of buffer when file on disk grows.
-With arg, turn Tail mode on iff arg is positive.
+With arg, turn Tail mode on if arg is positive, otherwise turn it off.
 
 When Tail mode is enabled, the tail of the file is constantly
 followed, as with the shell command `tail -f'.  This means that
diff --git a/lisp/bindings.el b/lisp/bindings.el
index 4ce58c204eb..3c7237a52fa 100644
--- a/lisp/bindings.el
+++ b/lisp/bindings.el
@@ -476,7 +476,7 @@ Menu of mode operations in the mode line.")
 (defvar minor-mode-alist nil "\
 Alist saying how to show minor modes in the mode line.
 Each element looks like (VARIABLE STRING);
-STRING is included in the mode line iff VARIABLE's value is non-nil.
+STRING is included in the mode line if VARIABLE's value is non-nil.
 
 Actually, STRING need not be a string; any possible mode-line element
 is okay.  See `mode-line-format'.")
diff --git a/lisp/custom.el b/lisp/custom.el
index c50fcb05f42..e5925dd18d0 100644
--- a/lisp/custom.el
+++ b/lisp/custom.el
@@ -642,7 +642,7 @@ this sets the local binding in that buffer instead."
     (funcall variable (if value 1 0))))
 
 (defun custom-quote (sexp)
-  "Quote SEXP iff it is not self quoting."
+  "Quote SEXP if it is not self quoting."
   (if (or (memq sexp '(t nil))
 	  (keywordp sexp)
 	  (and (listp sexp)
@@ -665,14 +665,14 @@ default value.  Otherwise, set it to nil.
 
 To actually save the value, call `custom-save-all'.
 
-Return non-nil iff the `saved-value' property actually changed."
+Return non-nil if the `saved-value' property actually changed."
   (custom-load-symbol symbol)
   (let* ((get (or (get symbol 'custom-get) 'default-value))
 	 (value (funcall get symbol))
 	 (saved (get symbol 'saved-value))
 	 (standard (get symbol 'standard-value))
 	 (comment (get symbol 'customized-variable-comment)))
-    ;; Save default value iff different from standard value.
+    ;; Save default value if different from standard value.
     (if (or (null standard)
 	    (not (equal value (condition-case nil
 				  (eval (car standard))
@@ -694,13 +694,13 @@ or else if it is different from the standard value, set the
 `customized-value' property to a list whose car evaluates to the
 default value.  Otherwise, set it to nil.
 
-Return non-nil iff the `customized-value' property actually changed."
+Return non-nil if the `customized-value' property actually changed."
   (custom-load-symbol symbol)
   (let* ((get (or (get symbol 'custom-get) 'default-value))
 	 (value (funcall get symbol))
 	 (customized (get symbol 'customized-value))
 	 (old (or (get symbol 'saved-value) (get symbol 'standard-value))))
-    ;; Mark default value as set iff different from old value.
+    ;; Mark default value as set if different from old value.
     (if (not (and old
                   (equal value (condition-case nil
                                    (eval (car old))
diff --git a/lisp/diff.el b/lisp/diff.el
index c612b2fb77c..75ae34d5f2a 100644
--- a/lisp/diff.el
+++ b/lisp/diff.el
@@ -62,7 +62,8 @@
 
 (defun diff-sentinel (code)
   "Code run when the diff process exits.
-CODE is the exit code of the process.  It should be 0 iff no diffs were found."
+CODE is the exit code of the process.  It should be 0 only if no diffs
+were found."
   (if diff-old-temp-file (delete-file diff-old-temp-file))
   (if diff-new-temp-file (delete-file diff-new-temp-file))
   (save-excursion
diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index fd57c4b8885..4d9849cd534 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -2006,8 +2006,8 @@ of marked files.  If KILL-ROOT is non-nil, kill DIRNAME as well."
 
 (defun dired-tree-lessp (dir1 dir2)
   ;; Lexicographic order on file name components, like `ls -lR':
-  ;; DIR1 < DIR2 iff DIR1 comes *before* DIR2 in an `ls -lR' listing,
-  ;;   i.e., iff DIR1 is a (grand)parent dir of DIR2,
+  ;; DIR1 < DIR2 if DIR1 comes *before* DIR2 in an `ls -lR' listing,
+  ;;   i.e., if DIR1 is a (grand)parent dir of DIR2,
   ;;   or DIR1 and DIR2 are in the same parentdir and their last
   ;;   components are string-lessp.
   ;; Thus ("/usr/" "/usr/bin") and ("/usr/a/" "/usr/b/") are tree-lessp.
diff --git a/lisp/double.el b/lisp/double.el
index 4b1d59ff1ec..0b5cf110fbd 100644
--- a/lisp/double.el
+++ b/lisp/double.el
@@ -186,7 +186,8 @@ use either \\[customize] or the function `double-mode'."
 ;;;###autoload
 (defun double-mode (arg)
   "Toggle Double mode.
-With prefix arg, turn Double mode on iff arg is positive.
+With prefix argument ARG, turn Double mode on if ARG is positive, otherwise
+turn it off.
 
 When Double mode is on, some keys will insert different strings
 when pressed twice.  See variable `double-map' for details."
diff --git a/lisp/ediff-diff.el b/lisp/ediff-diff.el
index 48cd7c79d4e..ec153fde625 100644
--- a/lisp/ediff-diff.el
+++ b/lisp/ediff-diff.el
@@ -867,7 +867,7 @@ one optional arguments, diff-number to refine.")
 	     (ediff-make-fine-diffs n 'noforce)
 	   (ediff-make-fine-diffs n 'skip)))
 
-	;; highlight iff fine diffs already exist
+	;; highlight if fine diffs already exist
 	((eq ediff-auto-refine 'off)
 	 (ediff-make-fine-diffs n 'skip))))
 
@@ -1459,7 +1459,7 @@ arguments to `skip-chars-forward'."
 
 
 (defun ediff-same-contents (d1 d2 &optional filter-re)
-  "Returns t iff D1 and D2 have the same content.
+  "Return t if D1 and D2 have the same content.
 D1 and D2 can either be both directories or both regular files.
 Symlinks and the likes are not handled.
 If FILTER-RE is non-nil, recursive checking in directories
diff --git a/lisp/files.el b/lisp/files.el
index dfa3cef384d..4d952f3f935 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3941,8 +3941,9 @@ prints a message in the minibuffer.  Instead, use `set-buffer-modified-p'."
 
 (defun toggle-read-only (&optional arg)
   "Change whether this buffer is visiting its file read-only.
-With arg, set read-only iff arg is positive.
-If visiting file read-only and `view-read-only' is non-nil, enter view mode."
+With prefix argument ARG, make the buffer read-only if ARG is
+positive, otherwise make it writable.  If visiting file read-only
+and `view-read-only' is non-nil, enter view mode."
   (interactive "P")
   (if (and arg
            (if (> (prefix-numeric-value arg) 0) buffer-read-only
@@ -4568,7 +4569,7 @@ FILENAME should lack slashes.  You can redefine this for customization."
 
 (defun wildcard-to-regexp (wildcard)
   "Given a shell file name pattern WILDCARD, return an equivalent regexp.
-The generated regexp will match a filename iff the filename
+The generated regexp will match a filename only if the filename
 matches that wildcard according to shell rules.  Only wildcards known
 by `sh' are supported."
   (let* ((i (string-match "[[.*+\\^$?]" wildcard))
diff --git a/lisp/font-lock.el b/lisp/font-lock.el
index 9eb4fdde2df..6bc5fd8716f 100644
--- a/lisp/font-lock.el
+++ b/lisp/font-lock.el
@@ -355,7 +355,7 @@ Each element in a user-level keywords list should have one of these forms:
 
 where MATCHER can be either the regexp to search for, or the function name to
 call to make the search (called with one argument, the limit of the search;
-it should return non-nil, move point, and set `match-data' appropriately iff
+it should return non-nil, move point, and set `match-data' appropriately if
 it succeeds; like `re-search-forward' would).
 MATCHER regexps can be generated via the function `regexp-opt'.
 
@@ -1068,7 +1068,7 @@ that tries to find such elements and move the boundaries such that they do
 not fall in the middle of one.
 Each function is called with no argument; it is expected to adjust the
 dynamically bound variables `font-lock-beg' and `font-lock-end'; and return
-non-nil iff it did make such an adjustment.
+non-nil if it did make such an adjustment.
 These functions are run in turn repeatedly until they all return nil.
 Put first the functions more likely to cause a change and cheaper to compute.")
 ;; Mark it as a special hook which doesn't use any global setting
@@ -1746,7 +1746,7 @@ A LEVEL of nil is equal to a LEVEL of 0, a LEVEL of t is equal to
   "Set fontification defaults appropriately for this mode.
 Sets various variables using `font-lock-defaults' (or, if nil, using
 `font-lock-defaults-alist') and `font-lock-maximum-decoration'."
-  ;; Set fontification defaults iff not previously set for correct major mode.
+  ;; Set fontification defaults if not previously set for correct major mode.
   (unless (and font-lock-set-defaults
 	       (eq font-lock-mode-major-mode major-mode))
     (setq font-lock-mode-major-mode major-mode)
diff --git a/lisp/frame.el b/lisp/frame.el
index 13c42ed5ad1..97133dee87c 100644
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -1310,9 +1310,9 @@ itself as a pre-command hook."
 
 (define-minor-mode blink-cursor-mode
   "Toggle blinking cursor mode.
-With a numeric argument, turn blinking cursor mode on iff ARG is positive.
-When blinking cursor mode is enabled, the cursor of the selected
-window blinks.
+With a numeric argument, turn blinking cursor mode on if ARG is positive,
+otherwise turn it off.  When blinking cursor mode is enabled, the
+cursor of the selected window blinks.
 
 Note that this command is effective only when Emacs
 displays through a window system, because then Emacs does its own
diff --git a/lisp/hilit-chg.el b/lisp/hilit-chg.el
index b1238b66419..a167b2bc1e7 100644
--- a/lisp/hilit-chg.el
+++ b/lisp/hilit-chg.el
@@ -131,7 +131,7 @@
 ;;   an example, if the value is `buffer-file-name' then all buffers
 ;;   who are visiting files are suitable, but others (like dired
 ;;   buffers) are not;
-;; * a list -- then the buffer is suitable iff its mode is in the
+;; * a list -- then the buffer is suitable if its mode is in the
 ;;   list, except if the first element is `not', in which case the test
 ;;   is reversed (i.e. it is a list of unsuitable modes).
 ;; * Otherwise, the buffer is suitable if its name does not begin with
diff --git a/lisp/ibuf-ext.el b/lisp/ibuf-ext.el
index b077342e5f5..7847bed6f2d 100644
--- a/lisp/ibuf-ext.el
+++ b/lisp/ibuf-ext.el
@@ -1331,7 +1331,7 @@ If a buffer has no filename, it is ignored.
 With no prefix arg, use the filename sans its directory of each marked file.
 With a zero prefix arg, use the complete filename of each marked file.
 With \\[universal-argument], use the filename of each marked file relative
-to `ibuffer-default-directory' iff non-nil, otherwise `default-directory'.
+to `ibuffer-default-directory' if non-nil, otherwise `default-directory'.
 
 You can then feed the file name(s) to other commands with \\[yank]."
   (interactive "p")
diff --git a/lisp/ibuffer.el b/lisp/ibuffer.el
index c4842b9d982..80133d227ab 100644
--- a/lisp/ibuffer.el
+++ b/lisp/ibuffer.el
@@ -1835,7 +1835,7 @@ If point is on a group name, this function operates on that group."
 
 (defun ibuffer-map-lines (function &optional nomodify group)
   "Call FUNCTION for each buffer.
-Don't set the ibuffer modification flag iff NOMODIFY is non-nil.
+Set the ibuffer modification flag unless NOMODIFY is non-nil.
 
 If optional argument GROUP is non-nil, then only call FUNCTION on
 buffers in filtering group GROUP.
@@ -2267,7 +2267,7 @@ If optional arg SILENT is non-nil, do not display progress messages."
 
 (defun ibuffer-quit ()
   "Quit this `ibuffer' session.
-Try to restore the previous window configuration iff
+Try to restore the previous window configuration if
 `ibuffer-restore-window-config-on-quit' is non-nil."
   (interactive)
   (if ibuffer-restore-window-config-on-quit
diff --git a/lisp/icomplete.el b/lisp/icomplete.el
index d1e8f9cc3f8..44c854f2f46 100644
--- a/lisp/icomplete.el
+++ b/lisp/icomplete.el
@@ -99,7 +99,7 @@ completions - see `icomplete-delay-completions-threshold'."
 (defcustom icomplete-minibuffer-setup-hook nil
   "*Icomplete-specific customization of minibuffer setup.
 
-This hook is run during minibuffer setup iff icomplete will be active.
+This hook is run during minibuffer setup if icomplete is active.
 It is intended for use in customizing icomplete for interoperation
 with other features and packages.  For instance:
 
@@ -168,7 +168,8 @@ except those on this list.")
 ;;;###autoload
 (define-minor-mode icomplete-mode
   "Toggle incremental minibuffer completion for this Emacs session.
-With a numeric argument, turn Icomplete mode on iff ARG is positive."
+With a numeric argument, turn Icomplete mode on if ARG is positive,
+otherwise turn it off."
   :global t :group 'icomplete
   (if icomplete-mode
       ;; The following is not really necessary after first time -
diff --git a/lisp/ido.el b/lisp/ido.el
index e5c4b644f95..ca44e99b594 100644
--- a/lisp/ido.el
+++ b/lisp/ido.el
@@ -898,7 +898,7 @@ See documentation of `walk-windows' for useful values.")
 (defcustom ido-minibuffer-setup-hook nil
   "*Ido-specific customization of minibuffer setup.
 
-This hook is run during minibuffer setup iff `ido' will be active.
+This hook is run during minibuffer setup if `ido' is active.
 It is intended for use in customizing ido for interoperation
 with other packages.  For instance:
 
diff --git a/lisp/image.el b/lisp/image.el
index cf909da0e95..480b5610311 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -342,7 +342,7 @@ Image types are symbols like `xbm' or `jpeg'."
 
 ;;;###autoload
 (defun image-type-auto-detected-p ()
-  "Return t iff the current buffer contains an auto-detectable image.
+  "Return t if the current buffer contains an auto-detectable image.
 This function is intended to be used from `magic-fallback-mode-alist'.
 
 The buffer is considered to contain an auto-detectable image if
diff --git a/lisp/imenu.el b/lisp/imenu.el
index 9aa1f5ea088..6c1de967e66 100644
--- a/lisp/imenu.el
+++ b/lisp/imenu.el
@@ -727,7 +727,7 @@ definitions, etc.  It contains a substring which is the name to
 appear in the menu.  See the info section on Regexps for more
 information.  REGEXP may also be a function, called without
 arguments.  It is expected to search backwards.  It shall return
-true and set `match-data' iff it finds another element.
+true and set `match-data' if it finds another element.
 
 INDEX points to the substring in REGEXP that contains the
 name (of the function, variable or type) that is to appear in the
diff --git a/lisp/info-look.el b/lisp/info-look.el
index 8ace7730a12..4ed13ba08e0 100644
--- a/lisp/info-look.el
+++ b/lisp/info-look.el
@@ -144,7 +144,7 @@ to `symbol', and the help mode defaults to the current major mode."
   (apply 'info-lookup-add-help* nil arg))
 
 (defun info-lookup-maybe-add-help (&rest arg)
-  "Add a help specification iff none is defined.
+  "Add a help specification if none is defined.
 See the documentation of the function `info-lookup-add-help'
 for more details."
   (apply 'info-lookup-add-help* t arg))
diff --git a/lisp/isearch.el b/lisp/isearch.el
index 7b90e319766..cc68ee297bd 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -819,7 +819,7 @@ NOPUSH is t and EDIT is t."
     (run-hooks 'isearch-mode-end-hook))
 
   ;; If there was movement, mark the starting position.
-  ;; Maybe should test difference between and set mark iff > threshold.
+  ;; Maybe should test difference between and set mark only if > threshold.
   (if (/= (point) isearch-opoint)
       (or (and transient-mark-mode mark-active)
 	  (progn
@@ -2321,7 +2321,7 @@ since they have special meaning in a regexp."
 ;;  - the direction of the current search is expected to be given by
 ;;    `isearch-forward';
 ;;  - the variable `isearch-error' is expected to be true
-;;    iff `isearch-string' is an invalid regexp.
+;;    only if `isearch-string' is an invalid regexp.
 
 (defvar isearch-lazy-highlight-overlays nil)
 (defvar isearch-lazy-highlight-wrapped nil)
diff --git a/lisp/iswitchb.el b/lisp/iswitchb.el
index 068f5fff2cd..233997285c9 100644
--- a/lisp/iswitchb.el
+++ b/lisp/iswitchb.el
@@ -396,7 +396,7 @@ See documentation of `walk-windows' for useful values.")
 (defcustom iswitchb-minibuffer-setup-hook nil
   "Iswitchb-specific customization of minibuffer setup.
 
-This hook is run during minibuffer setup iff `iswitchb' will be active.
+This hook is run during minibuffer setup if `iswitchb' is active.
 For instance:
 \(add-hook 'iswitchb-minibuffer-setup-hook
 	  '\(lambda () (set (make-local-variable 'max-mini-window-height) 3)))
@@ -1440,7 +1440,7 @@ This is an example function which can be hooked on to
     (iswitchb-to-end summaries)))
 
 (defun iswitchb-case ()
-  "Return non-nil iff we should ignore case when matching.
+  "Return non-nil if we should ignore case when matching.
 See the variable `iswitchb-case' for details."
   (if iswitchb-case
       (if (featurep 'xemacs)
@@ -1450,7 +1450,7 @@ See the variable `iswitchb-case' for details."
 ;;;###autoload
 (define-minor-mode iswitchb-mode
   "Toggle Iswitchb global minor mode.
-With arg, turn Iswitchb mode on if and only iff ARG is positive.
+With arg, turn Iswitchb mode on if ARG is positive, otherwise turn it off.
 This mode enables switching between buffers using substrings.  See
 `iswitchb' for details."
   nil nil iswitchb-global-map :global t :group 'iswitchb
diff --git a/lisp/log-edit.el b/lisp/log-edit.el
index 94d97abc8a5..c8ee5db812b 100644
--- a/lisp/log-edit.el
+++ b/lisp/log-edit.el
@@ -568,7 +568,7 @@ for more details."
 (defvar user-mail-address)
 (defun log-edit-changelog-ours-p ()
   "See if ChangeLog entry at point is for the current user, today.
-Return non-nil iff it is."
+Return non-nil if it is."
   ;; Code adapted from add-change-log-entry.
   (let ((name (or (and (boundp 'add-log-full-name) add-log-full-name)
 		  (and (fboundp 'user-full-name) (user-full-name))
diff --git a/lisp/printing.el b/lisp/printing.el
index f84a2112661..412f0b342fc 100644
--- a/lisp/printing.el
+++ b/lisp/printing.el
@@ -4943,9 +4943,9 @@ See `pr-visible-entry-alist'.")
 
 If FORCE is non-nil, update menus doesn't matter if `pr-ps-printer-alist',
 `pr-txt-printer-alist' or `pr-ps-utility-alist' were modified or not;
-otherwise, update PostScript printer menu iff `pr-ps-printer-menu-modified' is
-non-nil, update text printer menu iff `pr-txt-printer-menu-modified' is
-non-nil, and update PostScript File menus iff `pr-ps-utility-menu-modified' is
+otherwise, update PostScript printer menu if `pr-ps-printer-menu-modified' is
+non-nil, update text printer menu if `pr-txt-printer-menu-modified' is
+non-nil, and update PostScript File menus if `pr-ps-utility-menu-modified' is
 non-nil.
 
 If menu binding was not done, calls `pr-menu-bind'."
diff --git a/lisp/select.el b/lisp/select.el
index b1fa729a664..60259142522 100644
--- a/lisp/select.el
+++ b/lisp/select.el
@@ -178,7 +178,7 @@ Cut buffers are considered obsolete; you should use selections instead."
 If it is valid, set the register `r0' to 1, else set it to 0.")
 
 (defun string-utf-8-p (string)
-  "Return non-nil iff STRING is a unibyte string of valid UTF-8 sequence."
+  "Return non-nil if STRING is a unibyte string of valid UTF-8 sequence."
   (if (or (not (stringp string))
 	  (multibyte-string-p string))
       (error "Not a unibyte string: %s" string))
diff --git a/lisp/shadowfile.el b/lisp/shadowfile.el
index ee6dcc15b7e..d1de8be3910 100644
--- a/lisp/shadowfile.el
+++ b/lisp/shadowfile.el
@@ -285,7 +285,7 @@ information defining the cluster.  For interactive use, call
       ans)))
 
 (defun shadow-site-match (site1 site2)
-  "Non-nil iff SITE1 is or includes SITE2.
+  "Non-nil if SITE1 is or includes SITE2.
 Each may be a host or cluster name; if they are clusters, regexp of SITE1 will
 be matched against the primary of SITE2."
   (or (string-equal site1 site2) ; quick check
diff --git a/lisp/simple.el b/lisp/simple.el
index 6148a917f59..b71dffd3c35 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -4343,8 +4343,9 @@ The variable `selective-display' has a separate value for each buffer."
 
 (defun toggle-truncate-lines (&optional arg)
   "Toggle whether to fold or truncate long lines for the current buffer.
-With arg, truncate long lines iff arg is positive.
-Note that in side-by-side windows, truncation is always enabled."
+With prefix argument ARG, truncate long lines if ARG is positive,
+otherwise don't truncate them.  Note that in side-by-side
+windows, truncation is always enabled."
   (interactive "P")
   (setq truncate-lines
 	(if (null arg)
@@ -4367,11 +4368,11 @@ Note that in side-by-side windows, truncation is always enabled."
 
 (defun overwrite-mode (arg)
   "Toggle overwrite mode.
-With arg, turn overwrite mode on iff arg is positive.
-In overwrite mode, printing characters typed in replace existing text
-on a one-for-one basis, rather than pushing it to the right.  At the
-end of a line, such characters extend the line.  Before a tab,
-such characters insert until the tab is filled in.
+With prefix argument ARG, turn overwrite mode on if ARG is positive,
+otherwise turn it off.  In overwrite mode, printing characters typed
+in replace existing text on a one-for-one basis, rather than pushing
+it to the right.  At the end of a line, such characters extend the line.
+Before a tab, such characters insert until the tab is filled in.
 \\[quoted-insert] still inserts characters in overwrite mode; this
 is supposed to make it easier to insert characters when necessary."
   (interactive "P")
@@ -4383,14 +4384,13 @@ is supposed to make it easier to insert characters when necessary."
 
 (defun binary-overwrite-mode (arg)
   "Toggle binary overwrite mode.
-With arg, turn binary overwrite mode on iff arg is positive.
-In binary overwrite mode, printing characters typed in replace
-existing text.  Newlines are not treated specially, so typing at the
-end of a line joins the line to the next, with the typed character
-between them.  Typing before a tab character simply replaces the tab
-with the character typed.
-\\[quoted-insert] replaces the text at the cursor, just as ordinary
-typing characters do.
+With prefix argument ARG, turn binary overwrite mode on if ARG is
+positive, otherwise turn it off.  In binary overwrite mode, printing
+characters typed in replace existing text.  Newlines are not treated
+specially, so typing at the end of a line joins the line to the next,
+with the typed character between them.  Typing before a tab character
+simply replaces the tab with the character typed.  \\[quoted-insert]
+replaces the text at the cursor, just as ordinary typing characters do.
 
 Note that binary overwrite mode is not its own minor mode; it is a
 specialization of overwrite mode, entered by setting the
@@ -4405,9 +4405,9 @@ specialization of overwrite mode, entered by setting the
 
 (define-minor-mode line-number-mode
   "Toggle Line Number mode.
-With arg, turn Line Number mode on iff arg is positive.
-When Line Number mode is enabled, the line number appears
-in the mode line.
+With arg, turn Line Number mode on if arg is positive, otherwise
+turn it off.  When Line Number mode is enabled, the line number
+appears in the mode line.
 
 Line numbers do not appear for very large buffers and buffers
 with very long lines; see variables `line-number-display-limit'
@@ -4416,16 +4416,16 @@ and `line-number-display-limit-width'."
 
 (define-minor-mode column-number-mode
   "Toggle Column Number mode.
-With arg, turn Column Number mode on iff arg is positive.
-When Column Number mode is enabled, the column number appears
-in the mode line."
+With arg, turn Column Number mode on if arg is positive,
+otherwise turn it off.  When Column Number mode is enabled, the
+column number appears in the mode line."
   :global t :group 'mode-line)
 
 (define-minor-mode size-indication-mode
   "Toggle Size Indication mode.
-With arg, turn Size Indication mode on iff arg is positive.  When
-Size Indication mode is enabled, the size of the accessible part
-of the buffer appears in the mode line."
+With arg, turn Size Indication mode on if arg is positive,
+otherwise turn it off.  When Size Indication mode is enabled, the
+size of the accessible part of the buffer appears in the mode line."
   :global t :group 'mode-line)
 
 (defgroup paren-blinking nil
@@ -4960,7 +4960,7 @@ With prefix argument N, move N items (negative N means move backward)."
 These functions are called in order with four arguments:
 CHOICE - the string to insert in the buffer,
 BUFFER - the buffer in which the choice should be inserted,
-MINI-P - non-nil iff BUFFER is a minibuffer, and
+MINI-P - non-nil if BUFFER is a minibuffer, and
 BASE-SIZE - the number of characters in BUFFER before
 the string being completed.
 
@@ -5568,7 +5568,8 @@ See also `normal-erase-is-backspace'."
 
 (define-minor-mode visible-mode
   "Toggle Visible mode.
-With argument ARG turn Visible mode on iff ARG is positive.
+With argument ARG turn Visible mode on if ARG is positive, otherwise
+turn it off.
 
 Enabling Visible mode makes all invisible text temporarily visible.
 Disabling Visible mode turns off that effect.  Visible mode
diff --git a/lisp/skeleton.el b/lisp/skeleton.el
index 33e223e4b2b..4425bb0389a 100644
--- a/lisp/skeleton.el
+++ b/lisp/skeleton.el
@@ -209,8 +209,8 @@ If ELEMENT is a string or a character it gets inserted (see also
 		interesting point set by _
 	>	indent line (or interregion if > _) according to major mode
 	@	add position to `skeleton-positions'
-	&	do next ELEMENT iff previous moved point
-	|	do next ELEMENT iff previous didn't move point
+	&	do next ELEMENT if previous moved point
+	|	do next ELEMENT if previous didn't move point
 	-num	delete num preceding characters (see `skeleton-untabify')
 	resume:	skipped, continue here if quit is signaled
 	nil	skipped
diff --git a/lisp/strokes.el b/lisp/strokes.el
index 528ea477363..de4123453f5 100644
--- a/lisp/strokes.el
+++ b/lisp/strokes.el
@@ -1370,7 +1370,7 @@ If STROKES-MAP is not given, `strokes-global-map' will be used instead."
     (goto-char (point-min))))
 
 (defun strokes-alphabetic-lessp (stroke1 stroke2)
-  "T iff command name for STROKE1 is less than STROKE2's in lexicographic order."
+  "T if command name for STROKE1 is less than STROKE2's in lexicographic order."
   (let ((command-name-1 (symbol-name (cdr stroke1)))
 	(command-name-2 (symbol-name (cdr stroke2))))
     (string-lessp command-name-1 command-name-2)))
@@ -1520,7 +1520,7 @@ Encode/decode your strokes with \\[strokes-encode-buffer],
       (eq char ?*)))
 
 ;;(defsubst strokes-xor (a b)  ### Should I make this an inline function? ###
-;;  "T iff one and only one of A and B is non-nil; otherwise, returns nil.
+;;  "T if one and only one of A and B is non-nil; otherwise, returns nil.
 ;;NOTE: Don't use this as a numeric xor since it treats all non-nil
 ;;      values as t including `0' (zero)."
 ;;  (eq (null a) (not (null b))))
diff --git a/lisp/t-mouse.el b/lisp/t-mouse.el
index 12129d93602..99e42fe288b 100644
--- a/lisp/t-mouse.el
+++ b/lisp/t-mouse.el
@@ -271,7 +271,8 @@ The (secret) scrollbar interface is not implemented yet."
 ;;;###autoload
 (define-minor-mode t-mouse-mode
   "Toggle t-mouse mode to use the mouse in Linux consoles.
-With prefix arg, turn t-mouse mode on iff arg is positive.
+With prefix arg, turn t-mouse mode on if arg is positive, otherwise turn it
+off.
 
 This allows the use of the mouse when operating on a Linux console, in the
 same way as you can use the mouse under X11.
diff --git a/lisp/term.el b/lisp/term.el
index 4d1c660543a..370f643225b 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -470,7 +470,7 @@
 (defvar term-scroll-with-delete nil) ;; term-scroll-with-delete is t if
 ;;		forward scrolling should be implemented by delete to
 ;;		top-most line(s); and nil if scrolling should be implemented
-;;		by moving term-home-marker.  It is set to t iff there is a
+;;		by moving term-home-marker.  It is set to t if there is a
 ;;		(non-default) scroll-region OR the alternate buffer is used.
 (defvar term-pending-delete-marker) ;; New user input in line mode needs to
 ;;		be deleted, because it gets echoed by the inferior.
diff --git a/lisp/userlock.el b/lisp/userlock.el
index 17cbc0c3e55..8e4a6753a31 100644
--- a/lisp/userlock.el
+++ b/lisp/userlock.el
@@ -134,7 +134,7 @@ The buffer in question is current when this function is called."
 		 (setq answer nil))
 		((eq answer 'revert)
 		 (revert-buffer nil (not (buffer-modified-p)))
-					; ask confirmation iff buffer modified
+					; ask confirmation if buffer modified
 		 (signal 'file-supersession
 			 (list "File reverted" fn)))
 		((eq answer 'yield)
diff --git a/lisp/vc.el b/lisp/vc.el
index 835d2c50685..9065b2d2bcd 100644
--- a/lisp/vc.el
+++ b/lisp/vc.el
@@ -1103,7 +1103,7 @@ Used by `vc-restore-buffer-context' to later restore the context."
 	;; ;; We may want to reparse the compilation buffer after revert
 	;; (reparse (and (boundp 'compilation-error-list) ;compile loaded
 	;; 	      ;; Construct a list; each elt is nil or a buffer
-	;; 	      ;; iff that buffer is a compilation output buffer
+	;; 	      ;; if that buffer is a compilation output buffer
 	;; 	      ;; that contains markers into the current buffer.
 	;; 	      (save-current-buffer
 	;; 		(mapcar (lambda (buffer)
diff --git a/lisp/view.el b/lisp/view.el
index 2f541fbf360..f6722f53756 100644
--- a/lisp/view.el
+++ b/lisp/view.el
@@ -375,7 +375,8 @@ Use this argument instead of explicitly setting `view-exit-action'."
   ;; bindings instead of using the \\[] construction.  The reason for this
   ;; is that most commands have more than one key binding.
   "Toggle View mode, a minor mode for viewing text but not editing it.
-With ARG, turn View mode on iff ARG is positive.
+With prefix argument ARG, turn View mode on if ARG is positive, otherwise
+turn it off.
 
 Emacs commands that do not change the buffer contents are available as usual.
 Kill commands insert text in kill buffers but do not delete.  Other commands
diff --git a/lisp/whitespace.el b/lisp/whitespace.el
index c38b6563592..3ea8394b0b7 100644
--- a/lisp/whitespace.el
+++ b/lisp/whitespace.el
@@ -763,7 +763,7 @@ If timer is not set, then set it to scan the files in
 ;;;###autoload
 (define-minor-mode whitespace-global-mode
   "Toggle using Whitespace mode in new buffers.
-With ARG, turn the mode on iff ARG is positive.
+With ARG, turn the mode on if ARG is positive, otherwise turn it off.
 
 When this mode is active, `whitespace-buffer' is added to
 `find-file-hook' and `kill-buffer-hook'."
diff --git a/lisp/wid-edit.el b/lisp/wid-edit.el
index 04d91998e2a..6725144e682 100644
--- a/lisp/wid-edit.el
+++ b/lisp/wid-edit.el
@@ -483,7 +483,7 @@ new value.")
 
 ;;;###autoload
 (defun widgetp (widget)
-  "Return non-nil iff WIDGET is a widget."
+  "Return non-nil if WIDGET is a widget."
   (if (symbolp widget)
       (get widget 'widget-type)
     (and (consp widget)
@@ -500,7 +500,7 @@ Otherwise, just return the value."
       value)))
 
 (defun widget-member (widget property)
-  "Non-nil iff there is a definition in WIDGET for PROPERTY."
+  "Non-nil if there is a definition in WIDGET for PROPERTY."
   (cond ((plist-member (cdr widget) property)
 	 t)
 	((car widget)
@@ -1641,7 +1641,7 @@ If that does not exists, call the value of `widget-complete-field'."
       (widget-princ-to-string (widget-get widget :value))))
 
 (defun widget-default-active (widget)
-  "Return t iff this widget active (user modifiable)."
+  "Return t if this widget is active (user modifiable)."
   (or (widget-get widget :always-active)
       (and (not (widget-get widget :inactive))
 	   (let ((parent (widget-get widget :parent)))
diff --git a/lisp/window.el b/lisp/window.el
index 508d78caeb4..7a64588c076 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -120,7 +120,7 @@ bars (top, bottom, or nil)."
 PROC is called with a window as argument.
 
 Optional second arg MINIBUF t means count the minibuffer window even
-if not active.  MINIBUF nil or omitted means count the minibuffer iff
+if not active.  MINIBUF nil or omitted means count the minibuffer only if
 it is active.  MINIBUF neither t nor nil means not to count the
 minibuffer even if it is active.
 
@@ -165,7 +165,7 @@ value is returned.  If no window satisfies PREDICATE, DEFAULT is
 returned.
 
 Optional second arg MINIBUF t means count the minibuffer window even
-if not active.  MINIBUF nil or omitted means count the minibuffer iff
+if not active.  MINIBUF nil or omitted means count the minibuffer only if
 it is active.  MINIBUF neither t nor nil means not to count the
 minibuffer even if it is active.
 
@@ -833,7 +833,7 @@ means suspend autoselection."
 (defun mouse-autoselect-window-select ()
   "Select window with delayed window autoselection.
 If the mouse position has stabilized in a non-selected window, select
-that window.  The minibuffer window is selected iff the minibuffer is
+that window.  The minibuffer window is selected only if the minibuffer is
 active.  This function is run by `mouse-autoselect-window-timer'."
   (condition-case nil
       (let* ((mouse-position (mouse-position))
@@ -858,14 +858,14 @@ active.  This function is run by `mouse-autoselect-window-timer'."
 			;; If `mouse-autoselect-window' is positive, select
 			;; window if the window is the same as before.
 			(eq window mouse-autoselect-window-window))
-		   ;; Otherwise select window iff the mouse is at the same
+		   ;; Otherwise select window if the mouse is at the same
 		   ;; position as before.  Observe that the first test after
 		   ;; starting autoselection usually fails since the value of
 		   ;; `mouse-autoselect-window-position' recorded there is the
 		   ;; position where the mouse has entered the new window and
 		   ;; not necessarily where the mouse has stopped moving.
 		   (equal mouse-position mouse-autoselect-window-position))
-	       ;; The minibuffer is a candidate window iff it's active.
+	       ;; The minibuffer is a candidate window if it's active.
 	       (or (not (window-minibuffer-p window))
 		   (eq window (active-minibuffer-window))))
 	  ;; Mouse position has stabilized in non-selected window: Cancel
diff --git a/lisp/xt-mouse.el b/lisp/xt-mouse.el
index b9d711a3e4b..d14c9c85cd3 100644
--- a/lisp/xt-mouse.el
+++ b/lisp/xt-mouse.el
@@ -187,7 +187,8 @@
 ;;;###autoload
 (define-minor-mode xterm-mouse-mode
   "Toggle XTerm mouse mode.
-With prefix arg, turn XTerm mouse mode on iff arg is positive.
+With prefix arg, turn XTerm mouse mode on if arg is positive, otherwise turn
+it off.
 
 Turn it on to use Emacs mouse commands, and off to use xterm mouse commands.
 This works in terminal emulators compatible with xterm.  It only
diff --git a/mac/inc/m-mac.h b/mac/inc/m-mac.h
index a5a26cd000c..57bb0976b69 100644
--- a/mac/inc/m-mac.h
+++ b/mac/inc/m-mac.h
@@ -25,7 +25,7 @@ Boston, MA 02110-1301, USA.  */
    operating system this machine is likely to run.
    USUAL-OPSYS="<name of system .h file here, without the s- or .h>"  */
 
-/* Define WORDS_BIG_ENDIAN iff lowest-numbered byte in a word
+/* Define WORDS_BIG_ENDIAN if lowest-numbered byte in a word
    is the most significant byte.  */
 
 #define WORDS_BIG_ENDIAN
diff --git a/man/ChangeLog b/man/ChangeLog
index 6bd23a3694e..39895247477 100644
--- a/man/ChangeLog
+++ b/man/ChangeLog
@@ -1,3 +1,8 @@
+2007-08-08  Glenn Morris  <rgm@gnu.org>
+
+	* glossary.texi (Glossary): Deprecate `iff'.
+	* gnus.texi, sieve.texi: Replace `iff'.
+
 2007-08-07  Chong Yidong  <cyd@stupidchicken.com>
 
 	* files.texi (File Conveniences): Document point motion keys in Image