excise use of "iff" in the manual

* doc/ref/api-compound.texi:
* doc/ref/api-control.texi:
* doc/ref/api-data.texi:
* doc/ref/api-macros.texi:
* doc/ref/api-modules.texi:
* doc/ref/api-procedures.texi:
* doc/ref/api-scheduling.texi:
* doc/ref/api-smobs.texi:
* doc/ref/api-undocumented.texi:
* doc/ref/api-utility.texi:
* doc/ref/compiler.texi:
* doc/ref/intro.texi:
* doc/ref/scheme-using.texi:
* doc/ref/sxml.texi:
* doc/ref/web.texi: Change uses of "iff" to "if, otherwise".  Fixes bug
  10302.

doc/ref/api-compound.texi

@@ -300,7 +300,7 @@ depending on the datatype of their arguments.
 @rnindex list?
 @deffn {Scheme Procedure} list? x
 @deffnx {C Function} scm_list_p (x)
-Return @code{#t} iff @var{x} is a proper list, else @code{#f}.
+Return @code{#t} if @var{x} is a proper list, else @code{#f}.
 @end deffn
 
 The predicate @code{null?} is often used in list-processing code to
@@ -311,7 +311,7 @@ somehow deals with the elements of a list until the list satisfies
 @rnindex null?
 @deffn {Scheme Procedure} null? x
 @deffnx {C Function} scm_null_p (x)
-Return @code{#t} iff @var{x} is the empty list, else @code{#f}.
+Return @code{#t} if @var{x} is the empty list, else @code{#f}.
 @end deffn
 
 @deftypefn {C Function} int scm_is_null (SCM x)

doc/ref/api-control.texi

@@ -200,7 +200,7 @@ For this clause type, @var{test} may return multiple values, and
 @code{cond} ignores its boolean state; instead, @code{cond} evaluates
 @var{guard} and applies the resulting procedure to the value(s) of
 @var{test}, as if @var{guard} were the @var{consumer} argument of
-@code{call-with-values}.  Iff the result of that procedure call is a
+@code{call-with-values}.  If the result of that procedure call is a
 true value, it evaluates @var{expression} and applies the resulting
 procedure to the value(s) of @var{test}, in the same manner as the
 @var{guard} was called.

doc/ref/api-data.texi

@@ -2049,7 +2049,7 @@ number of one to eight digits.
 @rnindex char?
 @deffn {Scheme Procedure} char? x
 @deffnx {C Function} scm_char_p (x)
-Return @code{#t} iff @var{x} is a character, else @code{#f}.
+Return @code{#t} if @var{x} is a character, else @code{#f}.
 @end deffn
 
 Fundamentally, the character comparison operations below are
@@ -2057,31 +2057,31 @@ numeric comparisons of the character's code points.
 
 @rnindex char=?
 @deffn {Scheme Procedure} char=? x y
-Return @code{#t} iff code point of @var{x} is equal to the code point
+Return @code{#t} if code point of @var{x} is equal to the code point
 of @var{y}, else @code{#f}.
 @end deffn
 
 @rnindex char<?
 @deffn {Scheme Procedure} char<? x y
-Return @code{#t} iff the code point of @var{x} is less than the code
+Return @code{#t} if the code point of @var{x} is less than the code
 point of @var{y}, else @code{#f}.
 @end deffn
 
 @rnindex char<=?
 @deffn {Scheme Procedure} char<=? x y
-Return @code{#t} iff the code point of @var{x} is less than or equal
+Return @code{#t} if the code point of @var{x} is less than or equal
 to the code point of @var{y}, else @code{#f}.
 @end deffn
 
 @rnindex char>?
 @deffn {Scheme Procedure} char>? x y
-Return @code{#t} iff the code point of @var{x} is greater than the
+Return @code{#t} if the code point of @var{x} is greater than the
 code point of @var{y}, else @code{#f}.
 @end deffn
 
 @rnindex char>=?
 @deffn {Scheme Procedure} char>=? x y
-Return @code{#t} iff the code point of @var{x} is greater than or
+Return @code{#t} if the code point of @var{x} is greater than or
 equal to the code point of @var{y}, else @code{#f}.
 @end deffn
 
@@ -2099,32 +2099,32 @@ it cannot cover all cases for all languages.
 
 @rnindex char-ci=?
 @deffn {Scheme Procedure} char-ci=? x y
-Return @code{#t} iff the case-folded code point of @var{x} is the same
+Return @code{#t} if the case-folded code point of @var{x} is the same
 as the case-folded code point of @var{y}, else @code{#f}.
 @end deffn
 
 @rnindex char-ci<?
 @deffn {Scheme Procedure} char-ci<? x y
-Return @code{#t} iff the case-folded code point of @var{x} is less
+Return @code{#t} if the case-folded code point of @var{x} is less
 than the case-folded code point of @var{y}, else @code{#f}.
 @end deffn
 
 @rnindex char-ci<=?
 @deffn {Scheme Procedure} char-ci<=? x y
-Return @code{#t} iff the case-folded code point of @var{x} is less
+Return @code{#t} if the case-folded code point of @var{x} is less
 than or equal to the case-folded code point of @var{y}, else
 @code{#f}.
 @end deffn
 
 @rnindex char-ci>?
 @deffn {Scheme Procedure} char-ci>? x y
-Return @code{#t} iff the case-folded code point of @var{x} is greater
+Return @code{#t} if the case-folded code point of @var{x} is greater
 than the case-folded code point of @var{y}, else @code{#f}.
 @end deffn
 
 @rnindex char-ci>=?
 @deffn {Scheme Procedure} char-ci>=? x y
-Return @code{#t} iff the case-folded code point of @var{x} is greater
+Return @code{#t} if the case-folded code point of @var{x} is greater
 than or equal to the case-folded code point of @var{y}, else
 @code{#f}.
 @end deffn
@@ -2132,36 +2132,36 @@ than or equal to the case-folded code point of @var{y}, else
 @rnindex char-alphabetic?
 @deffn {Scheme Procedure} char-alphabetic? chr
 @deffnx {C Function} scm_char_alphabetic_p (chr)
-Return @code{#t} iff @var{chr} is alphabetic, else @code{#f}.
+Return @code{#t} if @var{chr} is alphabetic, else @code{#f}.
 @end deffn
 
 @rnindex char-numeric?
 @deffn {Scheme Procedure} char-numeric? chr
 @deffnx {C Function} scm_char_numeric_p (chr)
-Return @code{#t} iff @var{chr} is numeric, else @code{#f}.
+Return @code{#t} if @var{chr} is numeric, else @code{#f}.
 @end deffn
 
 @rnindex char-whitespace?
 @deffn {Scheme Procedure} char-whitespace? chr
 @deffnx {C Function} scm_char_whitespace_p (chr)
-Return @code{#t} iff @var{chr} is whitespace, else @code{#f}.
+Return @code{#t} if @var{chr} is whitespace, else @code{#f}.
 @end deffn
 
 @rnindex char-upper-case?
 @deffn {Scheme Procedure} char-upper-case? chr
 @deffnx {C Function} scm_char_upper_case_p (chr)
-Return @code{#t} iff @var{chr} is uppercase, else @code{#f}.
+Return @code{#t} if @var{chr} is uppercase, else @code{#f}.
 @end deffn
 
 @rnindex char-lower-case?
 @deffn {Scheme Procedure} char-lower-case? chr
 @deffnx {C Function} scm_char_lower_case_p (chr)
-Return @code{#t} iff @var{chr} is lowercase, else @code{#f}.
+Return @code{#t} if @var{chr} is lowercase, else @code{#f}.
 @end deffn
 
 @deffn {Scheme Procedure} char-is-both? chr
 @deffnx {C Function} scm_char_is_both_p (chr)
-Return @code{#t} iff @var{chr} is either uppercase or lowercase, else
+Return @code{#t} if @var{chr} is either uppercase or lowercase, else
 @code{#f}.
 @end deffn
 
@@ -2583,8 +2583,8 @@ string is not defined.
 
 @deffn {Scheme Procedure} char-set-contains? cs ch
 @deffnx {C Function} scm_char_set_contains_p (cs, ch)
-Return @code{#t} iff the character @var{ch} is contained in the
-character set @var{cs}.
+Return @code{#t} if the character @var{ch} is contained in the
+character set @var{cs}, or @code{#f} otherwise.
 @end deffn
 
 @deffn {Scheme Procedure} char-set-every pred cs

doc/ref/api-macros.texi

@@ -1,6 +1,6 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Guile Reference Manual.
-@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2009, 2010, 2011, 2012
+@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2009, 2010, 2011, 2012, 2013
 @c   Free Software Foundation, Inc.
 @c See the file guile.texi for copying conditions.
 
@@ -520,7 +520,8 @@ is impossible with @code{syntax-rules}, given the datum matching forms. But with
 @code{syntax-case} it is easy:
 
 @deffn {Scheme Procedure} identifier? syntax-object
-Returns @code{#t} iff @var{syntax-object} is an identifier.
+Returns @code{#t} if @var{syntax-object} is an identifier, or @code{#f}
+otherwise.
 @end deffn
 
 @example
@@ -690,13 +691,13 @@ macros can use to compare, generate, and query objects of this data
 type.
 
 @deffn {Scheme Procedure} bound-identifier=? a b
-Return @code{#t} iff the syntax objects @var{a} and @var{b} refer to the
-same lexically-bound identifier.
+Return @code{#t} if the syntax objects @var{a} and @var{b} refer to the
+same lexically-bound identifier, or @code{#f} otherwise.
 @end deffn
 
 @deffn {Scheme Procedure} free-identifier=? a b
-Return @code{#t} iff the syntax objects @var{a} and @var{b} refer to the
-same free identifier.
+Return @code{#t} if the syntax objects @var{a} and @var{b} refer to the
+same free identifier, or @code{#f} otherwise.
 @end deffn
 
 @deffn {Scheme Procedure} generate-temporaries ls
@@ -935,7 +936,7 @@ left-hand side of a @code{set!} expression, as in the following:
 (set! foo @var{val})
 ;; expands via
 (foo-transformer #'(set! foo @var{val}))
-;; iff foo-transformer is a "variable transformer"
+;; if foo-transformer is a "variable transformer"
 @end example
 
 As the example notes, the transformer procedure must be explicitly
@@ -1125,7 +1126,8 @@ for syntax-case.
 
 @deffn {Scheme Procedure} macro? obj
 @deffnx {C Function} scm_macro_p (obj)
-Return @code{#t} iff @var{obj} is a syntax transformer.
+Return @code{#t} if @var{obj} is a syntax transformer, or @code{#f}
+otherwise.
 
 Note that it's a bit difficult to actually get a macro as a first-class object;
 simply naming it (like @code{case}) will produce a syntax error. But it is

doc/ref/api-modules.texi

@@ -759,8 +759,8 @@ Return a variable initialized to value @var{init}.
 
 @deffn {Scheme Procedure} variable-bound? var
 @deffnx {C Function} scm_variable_bound_p (var)
-Return @code{#t} iff @var{var} is bound to a value.
-Throws an error if @var{var} is not a variable object.
+Return @code{#t} if @var{var} is bound to a value, or @code{#f}
+otherwise.  Throws an error if @var{var} is not a variable object.
 @end deffn
 
 @deffn {Scheme Procedure} variable-ref var
@@ -784,8 +784,8 @@ Unset the value of the variable @var{var}, leaving @var{var} unbound.
 
 @deffn {Scheme Procedure} variable? obj
 @deffnx {C Function} scm_variable_p (obj)
-Return @code{#t} iff @var{obj} is a variable object, else
-return @code{#f}.
+Return @code{#t} if @var{obj} is a variable object, else return
+@code{#f}.
 @end deffn
 
 

doc/ref/api-procedures.texi

@@ -157,7 +157,8 @@ appropriate module first, though:
 
 @deffn {Scheme Procedure} program? obj
 @deffnx {C Function} scm_program_p (obj)
-Returns @code{#t} iff @var{obj} is a compiled procedure.
+Returns @code{#t} if @var{obj} is a compiled procedure, or @code{#f}
+otherwise.
 @end deffn
 
 @deffn {Scheme Procedure} program-objcode program

doc/ref/api-scheduling.texi

@@ -247,7 +247,7 @@ Once @var{body} or @var{handler} returns, the return value is made the
 
 @deffn {Scheme Procedure} thread? obj
 @deffnx {C Function} scm_thread_p (obj)
-Return @code{#t} iff @var{obj} is a thread; otherwise, return
+Return @code{#t} ff @var{obj} is a thread; otherwise, return
 @code{#f}.
 @end deffn
 
@@ -267,7 +267,7 @@ specified; @code{#f} is returned otherwise).
 
 @deffn {Scheme Procedure} thread-exited? thread
 @deffnx {C Function} scm_thread_exited_p (thread)
-Return @code{#t} iff @var{thread} has exited.
+Return @code{#t} if @var{thread} has exited, or @code{#f} otherwise.
 @end deffn
 
 @c begin (texi-doc-string "guile" "yield")
@@ -376,7 +376,7 @@ The returned mutex will be recursive.
 
 @deffn {Scheme Procedure} mutex? obj
 @deffnx {C Function} scm_mutex_p (obj)
-Return @code{#t} iff @var{obj} is a mutex; otherwise, return
+Return @code{#t} if @var{obj} is a mutex; otherwise, return
 @code{#f}.
 @end deffn
 
@@ -481,7 +481,7 @@ Return a new condition variable.
 
 @deffn {Scheme Procedure} condition-variable? obj
 @deffnx {C Function} scm_condition_variable_p (obj)
-Return @code{#t} iff @var{obj} is a condition variable; otherwise,
+Return @code{#t} if @var{obj} is a condition variable; otherwise,
 return @code{#f}.
 @end deffn
 
@@ -702,7 +702,7 @@ implicitly bound to some definite value).
 
 @deffn {Scheme Procedure} fluid? obj
 @deffnx {C Function} scm_fluid_p (obj)
-Return @code{#t} iff @var{obj} is a fluid; otherwise, return
+Return @code{#t} if @var{obj} is a fluid; otherwise, return
 @code{#f}.
 @end deffn
 
@@ -726,7 +726,7 @@ Disassociate the given fluid from any value, making it unbound.
 
 @deffn {Scheme Procedure} fluid-bound? fluid
 @deffnx {C Function} scm_fluid_bound_p (fluid)
-Returns @code{#t} iff the given fluid is bound to a value, otherwise
+Returns @code{#t} if the given fluid is bound to a value, otherwise
 @code{#f}.
 @end deffn
 

doc/ref/api-smobs.texi

@@ -124,9 +124,9 @@ Else, signal an error.
 @end deftypefn
 
 @deftypefn {C Macro} int SCM_SMOB_PREDICATE (scm_t_bits tag, SCM exp)
-Return true iff @var{exp} is a smob instance of the type indicated by
-@var{tag}.  The expression @var{exp} can be evaluated more than once,
-so it shouldn't contain any side effects.
+Return true if @var{exp} is a smob instance of the type indicated by
+@var{tag}, or false otherwise.  The expression @var{exp} can be
+evaluated more than once, so it shouldn't contain any side effects.
 @end deftypefn
 
 @deftypefn {C Function} SCM scm_new_smob (scm_t_bits tag, void *data)

doc/ref/api-undocumented.texi

@@ -188,8 +188,8 @@ would modify regular hash tables. (@pxref{Hash Tables})
 @end deffn
 
 @deffn {Scheme Procedure} include-deprecated-features
-Return @code{#t} iff deprecated features should be included
-in public interfaces.
+Return @code{#t} if deprecated features should be included in public
+interfaces, or @code{#f} otherwise.
 @end deffn
 
 @deffn {Scheme Procedure} issue-deprecation-warning . msgs
@@ -202,7 +202,7 @@ they are printed in turn, each one followed by a newline.
 
 @deffn {Scheme Procedure} valid-object-procedure? proc
 @deffnx {C Function} scm_valid_object_procedure_p (proc)
-Return @code{#t} iff @var{proc} is a procedure that can be used with @code{set-object-procedure}.  It is always valid to use a closure constructed by @code{lambda}.
+Return @code{#t} ff @var{proc} is a procedure that can be used with @code{set-object-procedure}.  It is always valid to use a closure constructed by @code{lambda}.
 @end deffn
 
 @deffn {Scheme Procedure} %get-pre-modules-obarray

doc/ref/api-utility.texi

@@ -1,6 +1,6 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Guile Reference Manual.
-@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2011, 2012
+@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2011, 2012, 2013
 @c   Free Software Foundation, Inc.
 @c See the file guile.texi for copying conditions.
 
@@ -308,10 +308,10 @@ input.
 
 @deffn {Scheme Procedure} sorted? items less
 @deffnx {C Function} scm_sorted_p (items, less)
-Return @code{#t} iff @var{items} is a list or vector such that,
+Return @code{#t} if @var{items} is a list or vector such that,
 for each element @var{x} and the next element @var{y} of
 @var{items}, @code{(@var{less} @var{y} @var{x})} returns
-@code{#f}.
+@code{#f}.  Otherwise return @code{#f}.
 @end deffn
 
 @deffn {Scheme Procedure} sort items less

doc/ref/compiler.texi

@@ -580,9 +580,9 @@ variables. @var{vars} is a list of @code{(@var{name} @var{type}
 program's metadata and do not form part of a program's code path.
 @end deftp
 @deftp {Scheme Variable} <glil-mv-bind> vars rest
-A multiple-value binding of the values on the stack to @var{vars}. Iff
-@var{rest} is true, the last element of @var{vars} will be treated as
-a rest argument.
+A multiple-value binding of the values on the stack to @var{vars}.  If
+@var{rest} is true, the last element of @var{vars} will be treated as a
+rest argument.
 
 In addition to pushing a binding annotation on the stack, like
 @code{<glil-bind>}, an expression is emitted at compilation time to
@@ -789,7 +789,7 @@ objcode)} module.
 
 @deffn {Scheme Procedure} objcode? obj
 @deffnx {C Function} scm_objcode_p (obj)
-Returns @code{#f} iff @var{obj} is object code, @code{#f} otherwise.
+Returns @code{#f} if @var{obj} is object code, @code{#f} otherwise.
 @end deffn
 
 @deffn {Scheme Procedure} bytecode->objcode bytecode

doc/ref/intro.texi

@@ -1,6 +1,6 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Guile Reference Manual.
-@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2006, 2010, 2011
+@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2006, 2010, 2011, 2013
 @c   Free Software Foundation, Inc.
 @c See the file guile.texi for copying conditions.
 
@@ -288,21 +288,6 @@ classes, multiple inheritance and generic functions.
 @node Typographical Conventions
 @section Typographical Conventions
 
-We use some conventions in this manual.
-
-@itemize @bullet
-
-@item
-For some procedures, notably type predicates, we use ``iff'' to mean
-``if and only if''.  The construct is usually something like: `Return
-@var{val} iff @var{condition}', where @var{val} is usually
-``@nicode{#t}'' or ``non-@nicode{#f}''.  This typically means that
-@var{val} is returned if @var{condition} holds, and that @samp{#f} is
-returned otherwise.  To clarify: @var{val} will @strong{only} be
-returned when @var{condition} is true.
-@cindex iff
-
-@item
 In examples and procedure descriptions and all other places where the
 evaluation of Scheme expression is shown, we use some notation for
 denoting the output and evaluation results of expressions.
@@ -328,10 +313,6 @@ As you can see, this code prints @samp{1} (denoted by
 @samp{@print{}}), and returns @code{hooray} (denoted by
 @samp{@result{}}).
 
-@c Add other conventions here.
-
-@end itemize
-
 
 @c Local Variables:
 @c TeX-master: "guile.texi"

doc/ref/scheme-using.texi

@@ -125,7 +125,7 @@ The programmatic interface to value history is in a module:
 @end lisp
 
 @deffn {Scheme Procedure} value-history-enabled?
-Return true iff value history is enabled.
+Return true if value history is enabled, or false otherwise.
 @end deffn
 
 @deffn {Scheme Procedure} enable-value-history!

doc/ref/sxml.texi

@@ -381,13 +381,8 @@ Pearl. Proc ICFP'00, pp. 186-197.
 @deffn {Scheme Procedure} attlist-add attlist name-value
 @end deffn
 
-@deffn {Scheme Procedure} attlist-null? _
-@verbatim 
- -- Scheme Procedure: null? x
-     Return `#t' iff X is the empty list, else `#f'.
-
- 
-@end verbatim
+@deffn {Scheme Procedure} attlist-null? x
+Return @code{#t} if @var{x} is the empty list, else @code{#f}.
 @end deffn
 
 @deffn {Scheme Procedure} attlist-remove-top attlist

doc/ref/web.texi

@@ -351,8 +351,8 @@ parsing and serialization procedures.  If a header is unknown, its
 string name is simply its symbol name in title-case.
 
 @deffn {Scheme Procedure} known-header? sym
-Return @code{#t} iff @var{sym} is a known header, with associated
-parsers and serialization procedures.
+Return @code{#t} if @var{sym} is a known header, with associated
+parsers and serialization procedures, or @code{#f} otherwise.
 @end deffn
 
 @deffn {Scheme Procedure} header-parser sym
@@ -405,8 +405,8 @@ you want a header's value to be returned/written ``as-is''.
 @end deffn
 
 @deffn {Scheme Procedure} valid-header? sym val
-Return a true value iff @var{val} is a valid Scheme value for the header
-with name @var{sym}.
+Return a true value if @var{val} is a valid Scheme value for the header
+with name @var{sym}, or @code{#f} otherwise.
 @end deffn
 
 Now that we have a generic interface for reading and writing headers, we