Replace `iff' in doc-strings and comments.

15 files changed, 41 insertions, 35 deletions

diff --git a/lisp/progmodes/antlr-mode.el b/lisp/progmodes/antlr-mode.el
index 7fbeeab6ee..594b628ad4 100644
--- a/lisp/progmodes/antlr-mode.el
+++ b/lisp/progmodes/antlr-mode.el
@@ -568,7 +568,7 @@ The standard value contains the following functions as READ-FN:
 general value, or `antlr-read-boolean' with ARGs = \(PROMPT TABLE) which
 reads a boolean value or a member of TABLE.  PROMPT is the prompt when
 asking for a new value.  If non-nil, TABLE is a table for completion or
-a function evaluating to such a table.  The return value is quoted iff
+a function evaluating to such a table.  The return value is quoted if
 AS-STRING is non-nil and is either t or a symbol which is a member of
 `antlr-options-style'.")
 
@@ -2203,8 +2203,8 @@ part SUPER in the result of `antlr-file-dependencies'.  CLASSES is the
 part \(CLASS-SPEC ...) in the result of `antlr-directory-dependencies'.
 
 The result looks like \(OPTION WITH-UNKNOWN GLIB ...).  OPTION is the
-complete \"-glib\" option.  WITH-UNKNOWN has value t iff there is none
-or more than one grammar file for at least one super grammar.
+complete \"-glib\" option.  WITH-UNKNOWN is t if there is none or more
+than one grammar file for at least one super grammar.
 
 Each GLIB looks like \(GRAMMAR-FILE \. EVOCAB).  GRAMMAR-FILE is a file
 in which a super-grammar is defined.  EVOCAB is the value of the export
diff --git a/lisp/progmodes/cc-awk.el b/lisp/progmodes/cc-awk.el
index 997e6c44f1..3346767117 100644
--- a/lisp/progmodes/cc-awk.el
+++ b/lisp/progmodes/cc-awk.el
@@ -478,7 +478,7 @@
 
 (defun c-awk-get-NL-prop-prev-line (&optional do-lim)
   ;; Get the c-awk-NL-prop text-property from the previous line, calculating
-  ;; it if necessary.  Return nil iff we're already at BOB.
+  ;; it if necessary.  Return nil if we're at BOB.
   ;; See c-awk-after-if-for-while-condition-p for a description of DO-LIM.
   ;;
   ;; This function might do hidden buffer changes.
diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 44463a07f1..97dcc61460 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -5116,7 +5116,7 @@ comment at the start of cc-engine.el for more info."
   ;;     Foo::Foo (int b) : Base (b) {}
   ;; car ^                ^ point
   ;;
-  ;;   The cdr of the return value is non-nil iff a
+  ;;   The cdr of the return value is non-nil if a
   ;;   `c-typedef-decl-kwds' specifier is found in the declaration,
   ;;   i.e. the declared identifier(s) are types.
   ;;
diff --git a/lisp/progmodes/cc-vars.el b/lisp/progmodes/cc-vars.el
index a80833c004..76b0e5a898 100644
--- a/lisp/progmodes/cc-vars.el
+++ b/lisp/progmodes/cc-vars.el
@@ -186,7 +186,7 @@ the value set here overrides the style system (there is a variable
 		    (bq-process type)))))))))
 
 (defun c-valid-offset (offset)
-  "Return non-nil iff OFFSET is a valid offset for a syntactic symbol.
+  "Return non-nil if OFFSET is a valid offset for a syntactic symbol.
 See `c-offsets-alist'."
   (or (eq offset '+)
       (eq offset '-)
diff --git a/lisp/progmodes/cperl-mode.el b/lisp/progmodes/cperl-mode.el
index 3badfed5d4..cd7dabb882 100644
--- a/lisp/progmodes/cperl-mode.el
+++ b/lisp/progmodes/cperl-mode.el
@@ -3558,7 +3558,7 @@ modify syntax-type text property if the situation is too hard."
 	  (modify-syntax-entry starter (if (eq starter ?\\) "\\" ".") st)
 	  (if ender (modify-syntax-entry ender "." st))))
     ;; i: have 2 args, after end of the first arg
-    ;; i2: start of the second arg, if any (before delim iff `ender').
+    ;; i2: start of the second arg, if any (before delim if `ender').
     ;; ender: the last arg bounded by parens-like chars, the second one of them
     ;; starter: the starting delimiter of the first arg
     ;; go-forward: has 2 args, and the second part is empty
@@ -8090,7 +8090,7 @@ prototype \\&SUB	Returns prototype of the function given a reference.
 (defun cperl-beautify-regexp-piece (b e embed level)
   ;; b is before the starting delimiter, e before the ending
   ;; e should be a marker, may be changed, but remains "correct".
-  ;; EMBED is nil iff we process the whole REx.
+  ;; EMBED is nil if we process the whole REx.
   ;; The REx is guaranteed to have //x
   ;; LEVEL shows how many levels deep to go
   ;; position at enter and at leave is not defined
diff --git a/lisp/progmodes/cpp.el b/lisp/progmodes/cpp.el
index e85c475241..05b8b59c00 100644
--- a/lisp/progmodes/cpp.el
+++ b/lisp/progmodes/cpp.el
@@ -623,7 +623,8 @@ You can also use the keyboard accelerators indicated like this: [K]ey."
 
 (defun cpp-edit-toggle-known (arg)
   "Toggle writable status for known conditionals.
-With optional argument ARG, make them writable iff ARG is positive."
+With optional argument ARG, make them writable if ARG is positive,
+otherwise make them unwritable."
   (interactive "@P")
   (if (or (and (null arg) cpp-known-writable)
 	  (<= (prefix-numeric-value arg) 0))
@@ -633,7 +634,8 @@ With optional argument ARG, make them writable iff ARG is positive."
 
 (defun cpp-edit-toggle-unknown (arg)
   "Toggle writable status for unknown conditionals.
-With optional argument ARG, make them writable iff ARG is positive."
+With optional argument ARG, make them writable if ARG is positive,
+otherwise make them unwritable."
   (interactive "@P")
   (if (or (and (null arg) cpp-unknown-writable)
 	  (<= (prefix-numeric-value arg) 0))
diff --git a/lisp/progmodes/etags.el b/lisp/progmodes/etags.el
index 196c22b4a0..96af63849a 100644
--- a/lisp/progmodes/etags.el
+++ b/lisp/progmodes/etags.el
@@ -256,10 +256,10 @@ One argument, the tag info returned by `snarf-tag-function'.")
 (defvar tags-included-tables-function nil
   "Function to do the work of `tags-included-tables' (which see).")
 (defvar verify-tags-table-function nil
-  "Function to return t iff current buffer contains valid tags file.")
+  "Function to return t if current buffer contains valid tags file.")
 
 ;; Initialize the tags table in the current buffer.
-;; Returns non-nil iff it is a valid tags table.  On
+;; Returns non-nil if it is a valid tags table.  On
 ;; non-nil return, the tags table state variable are
 ;; made buffer-local and initialized to nil.
 (defun initialize-new-tags-table ()
@@ -417,7 +417,7 @@ file the tag was in."
 (defun tags-verify-table (file)
   "Read FILE into a buffer and verify that it is a valid tags table.
 Sets the current buffer to one visiting FILE (if it exists).
-Returns non-nil iff it is a valid table."
+Returns non-nil if it is a valid table."
   (if (get-file-buffer file)
       ;; The file is already in a buffer.  Check for the visited file
       ;; having changed since we last used it.
@@ -1219,8 +1219,8 @@ where they were found."
 	       (verify-tags-table-function . etags-verify-tags-table)
 	       ))))
 
-;; Return non-nil iff the current buffer is a valid etags TAGS file.
 (defun etags-verify-tags-table ()
+  "Return non-nil if the current buffer is a valid etags TAGS file."
   ;; Use eq instead of = in case char-after returns nil.
   (eq (char-after (point-min)) ?\f))
 
diff --git a/lisp/progmodes/fortran.el b/lisp/progmodes/fortran.el
index b986561376..16992c5452 100644
--- a/lisp/progmodes/fortran.el
+++ b/lisp/progmodes/fortran.el
@@ -1763,7 +1763,7 @@ If ALL is nil, only match comments that start in column > 0."
 ;; From: [email protected] (Ralf Fassel)
 ;; Test if TAB format continuation lines work.
 (defun fortran-is-in-string-p (where)
-  "Return non-nil iff WHERE (a buffer position) is inside a Fortran string."
+  "Return non-nil if WHERE (a buffer position) is inside a Fortran string."
   (save-excursion
     (goto-char where)
     (cond
diff --git a/lisp/progmodes/gdb-ui.el b/lisp/progmodes/gdb-ui.el
index 8f6be33446..c4d1446224 100644
--- a/lisp/progmodes/gdb-ui.el
+++ b/lisp/progmodes/gdb-ui.el
@@ -347,7 +347,8 @@ for `gdba'."
 
 (defun gdb-many-windows (arg)
   "Toggle the number of windows in the basic arrangement.
-With arg, display additional buffers iff arg is positive."
+With prefix argument ARG, display additional buffers if ARG is positive,
+otherwise use a single window."
   (interactive "P")
   (setq gdb-many-windows
 	(if (null arg)
@@ -363,7 +364,8 @@ With arg, display additional buffers iff arg is positive."
 
 (defun gdb-use-separate-io-buffer (arg)
   "Toggle separate IO for debugged program.
-With arg, use separate IO iff arg is positive."
+With prefix argument ARG, use separate IO if ARG is positive,
+otherwise do not."
   (interactive "P")
   (setq gdb-use-separate-io-buffer
 	(if (null arg)
@@ -664,7 +666,8 @@ line, and no execution takes place."
 
 (defun gdb-speedbar-auto-raise (arg)
   "Toggle automatic raising of the speedbar for watch expressions.
-With arg, automatically raise speedbar iff arg is positive."
+With prefix argument ARG, automatically raise speedbar if ARG is
+positive, otherwise don't automatically raise it."
   (interactive "P")
   (setq gdb-speedbar-auto-raise
 	(if (null arg)
@@ -1381,7 +1384,8 @@ directives."
 
 (defun gdb-find-source-frame (arg)
   "Toggle trying to find a source frame further up stack.
-With arg, look for a source frame further up stack iff arg is positive."
+With prefix argument ARG, look for a source frame further up
+stack if ARG is positive, otherwise don't look further up."
   (interactive "P")
   (setq gdb-find-source-frame
 	(if (null arg)
diff --git a/lisp/progmodes/gud.el b/lisp/progmodes/gud.el
index ec5b901f69..06bdd6a0b5 100644
--- a/lisp/progmodes/gud.el
+++ b/lisp/progmodes/gud.el
@@ -3353,7 +3353,7 @@ This event can be examined by forms in GUD-TOOLTIP-DISPLAY.")
 
 (defun gud-tooltip-dereference (&optional arg)
   "Toggle whether tooltips should show `* expr' or `expr'.
-With arg, dereference expr iff arg is positive."
+With arg, dereference expr if ARG is positive, otherwise do not derereference."
  (interactive "P")
   (setq gud-tooltip-dereference
 	(if (null arg)
diff --git a/lisp/progmodes/hideshow.el b/lisp/progmodes/hideshow.el
index 3f2580a5d4..fb990d6bf3 100644
--- a/lisp/progmodes/hideshow.el
+++ b/lisp/progmodes/hideshow.el
@@ -262,7 +262,7 @@ One of the following symbols:
   t       -- open both code and comment blocks
   nil     -- open neither code nor comment blocks
 
-This has effect iff `search-invisible' is set to `open'."
+This has effect only if `search-invisible' is set to `open'."
   :type '(choice (const :tag "open only code blocks" code)
                  (const :tag "open only comment blocks" comment)
                  (const :tag "open both code and comment blocks" t)
@@ -515,7 +515,7 @@ Optional arg REPOS-END means reposition at end."
   (goto-char (if repos-end end beg)))
 
 (defun hs-hide-block-at-point (&optional end comment-reg)
-  "Hide block iff on block beginning.
+  "Hide block if on block beginning.
 Optional arg END means reposition at end.
 Optional arg COMMENT-REG is a list of the form (BEGIN END) and
 specifies the limits of the comment, or nil if the block is not
@@ -679,7 +679,7 @@ Return point, or nil if original point was not in a block."
   (goto-char maxp))
 
 (defmacro hs-life-goes-on (&rest body)
-  "Evaluate BODY forms iff variable `hs-minor-mode' is non-nil.
+  "Evaluate BODY forms if variable `hs-minor-mode' is non-nil.
 In the dynamic context of this macro, `inhibit-point-motion-hooks'
 and `case-fold-search' are both t."
   `(when hs-minor-mode
diff --git a/lisp/progmodes/octave-mod.el b/lisp/progmodes/octave-mod.el
index adc1b44eda..3da3434cda 100644
--- a/lisp/progmodes/octave-mod.el
+++ b/lisp/progmodes/octave-mod.el
@@ -567,24 +567,24 @@ including a reproducible test case and send the message."
   (describe-function major-mode))
 
 (defsubst octave-in-comment-p ()
-  "Returns t if point is inside an Octave comment, nil otherwise."
+  "Return t if point is inside an Octave comment."
   (interactive)
   (save-excursion
     (nth 4 (parse-partial-sexp (line-beginning-position) (point)))))
 
 (defsubst octave-in-string-p ()
-  "Returns t if point is inside an Octave string, nil otherwise."
+  "Return t if point is inside an Octave string."
   (interactive)
   (save-excursion
     (nth 3 (parse-partial-sexp (line-beginning-position) (point)))))
 
 (defsubst octave-not-in-string-or-comment-p ()
-  "Returns t iff point is not inside an Octave string or comment."
+  "Return t if point is not inside an Octave string or comment."
   (let ((pps (parse-partial-sexp (line-beginning-position) (point))))
     (not (or (nth 3 pps) (nth 4 pps)))))
 
 (defun octave-in-block-p ()
-  "Returns t if point is inside an Octave block, nil otherwise.
+  "Return t if point is inside an Octave block.
 The block is taken to start at the first letter of the begin keyword and
 to end after the end keyword."
   (let ((pos (point)))
@@ -599,7 +599,7 @@ to end after the end keyword."
       (< pos (point)))))
 
 (defun octave-in-defun-p ()
-  "Returns t iff point is inside an Octave function declaration.
+  "Return t if point is inside an Octave function declaration.
 The function is taken to start at the `f' of `function' and to end after
 the end keyword."
   (let ((pos (point)))
diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index ca18f77297..7c1abaf223 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -348,7 +348,7 @@ comments and strings, or that point is within brackets/parens."
 		    (error nil))))))))
 
 (defun python-comment-line-p ()
-  "Return non-nil iff current line has only a comment."
+  "Return non-nil if current line has only a comment."
   (save-excursion
     (end-of-line)
     (when (eq 'comment (syntax-ppss-context (syntax-ppss)))
@@ -356,7 +356,7 @@ comments and strings, or that point is within brackets/parens."
       (looking-at (rx (or (syntax comment-start) line-end))))))
 
 (defun python-blank-line-p ()
-  "Return non-nil iff current line is blank."
+  "Return non-nil if current line is blank."
   (save-excursion
     (beginning-of-line)
     (looking-at "\\s-*$")))
@@ -850,7 +850,7 @@ multi-line bracketed expressions."
   "Skip out of any nested brackets.
 Skip forward if FORWARD is non-nil, else backward.
 If SYNTAX is non-nil it is the state returned by `syntax-ppss' at point.
-Return non-nil iff skipping was done."
+Return non-nil if skipping was done."
   (let ((depth (syntax-ppss-depth (or syntax (syntax-ppss))))
 	(forward (if forward -1 1)))
     (unless (zerop depth)
@@ -1191,7 +1191,7 @@ local value.")
     (define-key map "\C-c\C-l" 'python-load-file)
     (define-key map "\C-c\C-v" 'python-check)
     ;; Note that we _can_ still use these commands which send to the
-    ;; Python process even at the prompt iff we have a normal prompt,
+    ;; Python process even at the prompt provided we have a normal prompt,
     ;; i.e. '>>> ' and not '... '.  See the comment before
     ;; python-send-region.  Fixme: uncomment these if we address that.
 
diff --git a/lisp/progmodes/which-func.el b/lisp/progmodes/which-func.el
index 922de2d54c..7d953be1d5 100644
--- a/lisp/progmodes/which-func.el
+++ b/lisp/progmodes/which-func.el
@@ -232,7 +232,7 @@ It creates the Imenu index for the buffer, if necessary."
 When Which Function mode is enabled, the current function name is
 continuously displayed in the mode line, in certain major modes.
 
-With prefix ARG, turn Which Function mode on iff arg is positive,
+With prefix ARG, turn Which Function mode on if arg is positive,
 and off otherwise."
   :global t :group 'which-func
   (if which-function-mode
diff --git a/lisp/progmodes/xscheme.el b/lisp/progmodes/xscheme.el
index 0beca9e985..a820ca4ced 100644
--- a/lisp/progmodes/xscheme.el
+++ b/lisp/progmodes/xscheme.el
@@ -868,7 +868,7 @@ Control returns to the top level rep loop."
     (sleep-for 1)))
 
 (defun xscheme-process-running-p ()
-  "True iff there is a Scheme process whose status is `run'."
+  "True if there is a Scheme process whose status is `run'."
   (let ((process (get-process xscheme-process-name)))
     (and process
 	 (eq (process-status process) 'run))))
@@ -882,7 +882,7 @@ Control returns to the top level rep loop."
     (and buffer (get-buffer-window buffer))))
 
 (defun xscheme-process-buffer-current-p ()
-  "True iff the current buffer is the Scheme process buffer."
+  "True if the current buffer is the Scheme process buffer."
   (eq (xscheme-process-buffer) (current-buffer)))
 
 ;;;; Process Filter Operations