Replace `iff'.

etc/GNUS-NEWS

@@ -30,7 +30,7 @@ or remove them using `make remove-installed-shadows'.
 
 Use `make.bat' if you want to install Gnus under MS Windows, the first
 argument to the batch-program should be the directory where `xemacs.exe'
-respectively `emacs.exe' is located, iff you want to install Gnus after
+respectively `emacs.exe' is located, if you want to install Gnus after
 compiling it, give `make.bat' `/copy' as the second parameter.
 
 `make.bat' has been rewritten from scratch, it now features automatic
@@ -308,7 +308,7 @@ as external parts.
 
 ** Gnus no longer generate the Sender: header automatically.
 
-Earlier it was generated iff the user configurable email address was
+Earlier it was generated when the user configurable email address was
 different from the Gnus guessed default user address.  As the guessing
 algorithm is rarely correct these days, and (more controversially) the
 only use of the Sender: header was to check if you are entitled to

etc/NEWS

@@ -3558,8 +3558,8 @@ that is, floats are compared by value and other elements with `eq'.
 
 *** New functions `string-or-null-p' and `booleanp'.
 
-`string-or-null-p' returns non-nil iff OBJECT is a string or nil.
-`booleanp' returns non-nil iff OBJECT is t or nil.
+`string-or-null-p' returns non-nil if OBJECT is a string or nil.
+`booleanp' returns non-nil if OBJECT is t or nil.
 
 *** `makehash' is now obsolete.  Use `make-hash-table' instead.
 

etc/NEWS.1-17

@@ -1208,7 +1208,7 @@ whether and where a line has a comment.
 
 * New function `auto-save-file-name-p'
 
-Should return non-`nil' iff given a string which is the name of an
+Should return non-`nil' if given a string which is the name of an
 auto-save file (sans directory name).  If you redefine
 `make-auto-save-file-name', you should redefine this accordingly.  By
 default, this function returns `t' for filenames beginning with

etc/NEWS.19

@@ -5133,8 +5133,8 @@ using X).
 ** It is now simpler to tell Emacs to display accented characters under
 X windows.  M-x standard-display-european toggles the display of
 buffer text according to the ISO Latin-1 standard.  With a prefix
-argument, this command enables European character display iff the
-argument is positive.
+argument, this command enables European character display if and only
+if the argument is positive.
 
 ** The `-i' command-line argument tells Emacs to use a picture of the
 GNU gnu as its icon, instead of letting the window manager choose an

etc/NEWS.21

@@ -2502,7 +2502,7 @@ 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 if
 it is active.  MINIBUF neither t nor nil means not to count the
 minibuffer even if it is active.